State Grasp Device, and Switching Control Device of Power Switching Apparatus Employing the State Grasp Device

ABSTRACT

A state grasp device that needs no optical adjustment, and can be downsized. An exciting current waveform of an opening electromagnetic coil of an electromagnetic operating set functioning to drive a moving contact of a switching device includes an inflection point appearing subsequently to a maximum value, the inflection point taking place at the time of the contact being parted. Accordingly, a wear amount of contact from the change over time can be obtained. A position of the inflection point is obtained, for example, by focusing the rate of change in current; and a wear amount of a switching contact is obtained from the change over time of a time when the inflection point takes place. With the device, the use of a mechanical detection device, such as an optical detector, can be eliminated.

TECHNICAL FIELD

The present invention relates to a state grasp device for grasping astate, e.g., wear amount of a switching contact of a power circuitbreaker of an operated apparatus or an electromagnetic operating systemin the case where the operated apparatus is operated by theelectromagnetic operating system, and further relates to a switchingcontrol device of a power switching apparatus provided with this stategrasp device.

BACKGROUND ART

As a measuring device functioning to measure a wear of a switchingcontact, being one of state quantities of a breaker, for example, thereis the one in which an indicator is attached to a driving rod adjacentto a driving coil of an electromagnetic operating mechanism, a positionthereof is detected using an optical detector, and a displacement of theindicator from at an initial position due to the wear of a contact(refer to, for example, Patent Document 1).

Patent Document 1: British Patent Application laid-open underPublication No. 2350724 (15-20 lines on page 5, and FIG. 4)

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

Since the conventional measuring device for measuring a wear amount of aswitching contact is arranged as described above, an optical detectorbecomes necessary, resulting in a large-scaled apparatus. In addition tothis, it is required to hold an indicator being optically pointed. Tomeet this requirement, an optical adjustment for controlling an opticalaxis has to be done. Further, since a wear amount of contact is ofseveral millimeters at most, the adjustment for eliminating the axisdeviation has to be done with high accuracy. Moreover, supposing thatthere are provided two detectors in one operating mechanism and thereare provided three operating mechanisms in a three-phase power switchingapparatus with one operating mechanism located in each phase, sixdetectors will be needed, resulting in a problem of a larger-scaled andfurther expensive device.

The present invention was made to solve the above-discussed problems,and has an object of obtaining a state grasp device for grasping a stateof an electromagnetic operating system or an operated apparatus, thestate grasp device needing no optical adjustment and capable of beingdownsized. Further, the invention has another object of obtaining astate grasp device for a power switching apparatus that needs no opticaladjustment as well as can be downsized. Furthermore, the invention hasanother object of obtaining a switching control device of a powerswitching apparatus that uses this state grasp device, and can achieve alonger operating life of switching contact.

Means of Solution to the Problems

A state grasp device according to the invention, which is disposed in anelectromagnetic operating system that includes a fixed iron core; amoving iron core constructed movably with respect to this fixed ironcore; and an electromagnetic coil that is excited by a driving powersupply, and causes the moving iron core to travel, thereby driving anoperated apparatus that is connected to the moving iron core. The stategrasp device comprises measurement means for measuring a current flowingthrough the electromagnetic coil or a voltage to be generated at theelectromagnetic coil, and search means for obtaining change informationon an output waveform from this measurement means; and estimates a stateof the operated apparatus or electromagnetic operating system on thebasis of change information from this search means.

Further, in the state grasp device of a power switching apparatusaccording to the invention, an electromagnetic operating system thereofdrives a moving contact of a switching contact of the switchingapparatus, being an operated apparatus; and search means thereofincludes at least one of a first inflection point search means forobtaining, as a contact motion start time, a time when a firstinflection point that appears subsequently to the maximum value of acurrent waveform provided from current measurement means takes place,and a second inflection point search means for obtaining, as a contactmovement completion time, a time when a second inflection point, whichtakes place after the contact motion start time and at which a currentwaveform becomes the minimum, takes place.

Furthermore, in a switching control device of a power switchingapparatus according to the invention, an electromagnetic operatingsystem thereof drives a moving contact of a switching contact of a powerswitching apparatus, being an operated apparatus, and is provided withan opening electromagnetic coil and a closing electromagnetic coil to beexcited with an electric charge having been stored in a capacitor as anelectromagnetic coil;

search means thereof comprises at least one of the first inflectionpoint search means obtaining as a contact motion start time a time whenthe first inflection point takes place, which point appears subsequentlyto the maximum value of a current waveform provided by the currentmeasurement means, and the second inflection point search meansobtaining as a contact movement completion time a time when the secondinflection point, which takes place subsequently to the contact motionstart time and at which a current waveform becomes the minimum, takesplace; and

there are provided closing time period prediction means for predicting aclosing completion time period when the closing electromagnetic coil isexcited next on the basis of at least one of the contact motion starttime and the contact movement completion time and at least one of acharge voltage of the capacitor and temperature information of the powerswitching apparatus; and timing control means for controlling timing ofexciting the closing electromagnetic coil next on the basis of theclosing completion prediction time period.

EFFECT OF THE INVENTION

In the state grasp device according to the invention, which is disposedin an electromagnetic operating system that includes a fixed iron core;a moving iron core constructed movably with respect to this fixed ironcore; and an electromagnetic coil that is excited by a driving powersupply, and causes the moving iron core to travel, thereby driving anoperated apparatus that is connected to the moving iron core; the stategrasp device comprises measurement means for measuring a current flowingthrough the electromagnetic coil or a voltage to be generated at theelectromagnetic coil, and search means for obtaining change informationon an output waveform from this measurement means; and estimates a stateof the operated apparatus or electromagnetic operating system on thebasis of change information from this search means. As a result, it ispossible to estimate states of an operated apparatus or anelectromagnetic operating system with a device that needs no opticaladjustment, as well as is small-sized.

Further, in the state grasp device of a power switching apparatusaccording to the invention, an electromagnetic operating system thereofdrives a moving contact of a switching contact of a power switchingapparatus, being an operated apparatus; and search means thereof obtainsat least one of a first inflection point search means for obtaining as acontact motion start time a time when a first inflection point thatappears subsequently to the maximum value of a current waveform providedfrom current measurement means takes place, and a second inflectionpoint search means for obtaining as a contact movement completion time atime when a second inflection point, which takes place after the contactmotion start time and at which a current waveform becomes the minimum,takes place. As a result, it is possible to obtain a contact motionstart time or a contact movement completion time to grasp states of apower switching apparatus with a device that needs no opticaladjustment, as well as is small-sized.

Furthermore, in a switching control device of a power switchingapparatus according to the invention, an electromagnetic operatingsystem thereof drives a moving contact of a switching contact of a powerswitching apparatus, being an operated apparatus, and is provided withan opening electromagnetic coil and a closing electromagnetic coil to beexcited with an electric charge having been stored in a capacitor as anelectromagnetic coil; search means thereof comprises at least one of thefirst inflection point search means obtaining as a contact motion starttime a time when the first inflection point takes place which pointappears subsequently to the maximum value of a current waveform providedby the current measurement means, and the second inflection point searchmeans obtaining as a contact movement completion time a time when thesecond inflection point, which takes place subsequently to the contactmotion start time and at which a current waveform becomes the minimum,takes place; and there are provided closing time period prediction meansfor predicting a closing completion time period when the closingelectromagnetic coil is excited next on the basis of at least one of thecontact motion start time and the contact movement completion time, andat least one of a charge voltage of the capacitor and temperatureinformation of the power switching apparatus; and timing control meansfor controlling timing of exciting the closing electromagnetic coil nexton the basis of the closing completion prediction time period. As aresult, it is possible to make longer an operating life of a switchingcontact of the power switching apparatus.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

FIGS. 1 to 9 show a first preferred embodiment of the present invention.FIG. 1 is a schematic view of a vacuum circuit breaker, being anoperated apparatus employing an electromagnetic operating mechanism.FIGS. 2 are state views showing switching states of the vacuum circuitbreaker. FIG. 3 is an enlarged view of an electromagnetic operatingmechanism. FIG. 4 is a schematic diagram showing an arrangement of acontact wear-measuring device of the vacuum circuit breaker. FIG. 5 is acharacteristic chart indicating current flowing through an opening coiland a stroke of a moving iron core. FIG. 6 is a characteristic chartindicating a mass and a contact pressure of contacts at the time ofoperation of the vacuum circuit breaker. FIG. 7 is a flowchart forexplaining the operation. FIG. 8 is a characteristic chart indicatingthe rate of change in current flowing through an opening coil. FIG. 9 isan explanatory chart indicating current waveforms flowing through theopening coil and strokes in comparison between when contacts show nowear and when the contacts show some wear.

With reference to FIG. 1, a vacuum valve 3 forming a vacuum circuitbreaker contains switching contacts 5 in a vacuum container. Theswitching contact 5 includes a moving contact Sb that is disposed inopposition to a stationary contact 5 a, which is located at the left ofFIG. 1, with a predetermined gap therebetween in lateral direction ofFIG. 1, being an axial direction. A driving rod 7 is fixed to the movingcontact 5 b, and the moving contact 5 b and the driving rod 7 form amoving part 6. This moving part 6 is connected to a moving iron core 16of the later-described electromagnetic operating mechanism via apressure spring 8 and a spring bearing 9.

The electromagnetic operating mechanism 10 (refer to FIG. 3 as well)includes a closing coil 13, an opening coil 14, and a moving iron core16. The closing coil 13 and opening coil 14 acting as drivingelectromagnetic coils are wound in a hollow rectangular configuration,and they are disposed with a predetermined distance therebetween inaxial direction. The moving iron core 16 having a rectangular crosssection that is made of ferromagnetic material is disposed in an axiallymovable manner at each axially central portion of the closing coil 13and the opening coil 14. A plate-like permanent magnet 16 a is attachedonto the peripheral portion of the moving iron core 16 (refer to FIG.3). A drive power-supply unit 20 includes a closing capacitor 23, anopening capacitor 24, a closing command switch 27, and an openingcommand switch 28. Furthermore, there is provided a current measuringinstrument 32 acting as current measuring means on a connection line 31providing a connection between the opening capacitor 24 of the drivepower supply unit 20 and the opening coil 14.

A contact-wear measuring device 33 acting as characteristic amount graspdevice of the power switching apparatus is connected to the currentmeasuring instrument 32. The contact wear measuring device 33, of whichdetailed arrangement is shown in FIG. 4, includes an AD converter 33 a,an opening start point search means 33 b acting as a first inflectionpoint search means, a memory 33 c, and contact wear calculation means 33d and contact wear determination means 33 e acting as characteristicamount grasp means. Each function of the opening start point searchmeans 33 b and the contact wear calculation means 33 d is performed in aCPU. The opening start point search means 33 b or the contact wearcalculation means 33 d includes an adder and a multiplier, not shown,and is capable of an arithmetical operation. Numerical values, being atarget of the arithmetical operation, are placed in a register variable,being a temporary storage region in an internal part of the openingstart point search means 33 b or the contact wear calculation means 33 dfrom the memory 33 d. Operation results are temporarily placed in theregister variable, and thereafter are transferred to the memory 33 c.

Now, switching operation of the vacuum circuit breaker is described.With reference to FIG. 1, the closing capacitor 23 and the openingcapacitor 24 of the drive power-supply unit 20 are regularly chargedwith a predetermined voltage. When a closing command switch 27 ispressed to provide a closing command in the state in which the movingcontact 5 b is parted, shown in FIG. 1 and FIG. 2(a) , an electriccharge having been charged in the closing capacitor 23 is supplied tothe closing coil 13. Then, the current flowing through the closing coil13 causes the moving iron core 16 to drive axially to the left of FIG.1, and brings the moving contact 5 b in contact with the stationarycontact 5 a via the pressure spring 8 and the driving rod 7 to beclosed. At this time, the moving contact 5 b comes to be in contact withthe stationary contact 5 b to become in the state of FIG. 2(b),thereafter the pressure spring 8 is pressed further to come into thestate of FIG. 2(c) in which a contact pressure between the contacts isobtained, and is kept in this state by the magnetic flux provided by thepermanent magnet 16 a that is attached to the moving iron core 16 tobecome in the closed state.

When an opening command switch 28 is pressed to provide an openingcommand in this closed state, an electric charge having been charged inthe opening capacitor 24 is supplied to the opening coil 14 via theconnection line 31. Then, the current flowing through the opening coil14 causes the moving iron core 16 to be driven axially to the right ofFIG. 1 to change from the state of FIG. 2(C) first to the state of FIG.2(b). During this time period, the pressure spring 8 having been pressedjust extends even if the moving iron core 16 travels to the right, andthe moving contact 5 b and the driving rode 7 on the vacuum valve 3 sideare not moved. Thereafter, when the moving iron core 16 travels furtherto the right, the moving contact 5 b, the driving rod 7, the pressurespring 8, the spring bearing 9, and the moving iron core 16 moverightward all together. The moving contact 5 b is parted from thestationary contact 5 a to be in the state of FIG. 2(a), and held by themagnetic flux of the permanent magnet 16 a that is attached to themoving iron core 16 to become in the open state.

Prior to the description of operations of the contact wear measuringdevice 33, described hereinafter are current flowing through the openingcoil 14 when a vacuum circuit breaker is open and the change in strokeof the moving iron core 16. When the vacuum circuit breaker is closed,as described above, the pressure spring 8 is pressed by means of themoving iron core 16, and the contacts 5 a and 5 b are maintained in thestate in which a contact pressure therebetween is held by the action ofthe magnetic flux indicated by the black arrows in FIG. 3 of thepermanent magnet 16 a (FIG. 2(c)). At this moment, the current in adirection of counteracting the above-mentioned magnetic flux indicatedby the black arrows of the permanent magnet is made to flow through theopening coil 14. Thus, the above-mentioned hold magnetic force isattenuated, and the moving iron core 16 travels in a direction ofopening (rightward direction of FIGS. 1 to 3) by the electromagneticattraction that is generated by the action of magnetic flux indicated bythe white arrows.

When the moving iron cores 16 starts traveling, first the spring bearing9 that is connected to the moving iron core 16 comes to travel.Accordingly, an inertia of masses of the moving iron core 16, the springbearing 9, the pressure spring 8, and a connection rod providing aconnection between the moving iron core 16 and the spring bearing 9, isexerted on the electromagnetic operating mechanism 10. Subsequently,when the moving iron core 16 travels rightward by a predetermineddistance, the spring bearing 9 comes to be in contact with the drivingrod 7 resided on the side of the vacuum valve 3. That is, the situationschange from the state of FIG. 2(c) to the state of FIG. 2(b). On andafter this moment, the whole of moving members from the moving iron core16 to the moving contact 5 b travels as an integral part, and a movingmass is sharply increased as shown in FIG. 6. This inertia will beexerted on the electromagnetic operating mechanism 10.

These operations are based on the following circuit equations (1) (2)and equation of motion (3). Masses and loads relating to the drivesystem change in a discontinuous manner during a series of motions ofthe moving iron core 16, the moving contact 5 b or the like, and thischange causes a waveform of the current flowing through the opening coil14 to change. The present invention focuses on this phenomenon.

The circuit equation (1) is an equation that can be satisfied in thestate in which the moving part 6 is at rest before being driven andafter having been driven. The circuit equation (2) is an equation thatcan be satisfied in the state in which a speed electromotive force termis generated during driving. $\begin{matrix}\left\lbrack {{Equation}\quad 1} \right\rbrack & \quad \\{{{{I(t)} \cdot R} + {\frac{\mathbb{d}{\phi\left( {{I(t)},{z(t)}} \right)}}{\mathbb{d}I} \cdot \frac{\mathbb{d}I}{\mathbb{d}t}}} = E} & (1) \\{{{{I(t)} \cdot R} + {\frac{\mathbb{d}{\phi\left( {{I(t)},{z(t)}} \right)}}{\mathbb{d}I} \cdot \frac{\mathbb{d}I}{\mathbb{d}t}} + {\frac{\mathbb{d}{\phi\left( {{I(t)},{z(t)}} \right)}}{\mathbb{d}I} \cdot \frac{\mathbb{d}z}{\mathbb{d}t}}} = E} & (2) \\{{{m\left( {z(t)} \right)}\frac{\mathbb{d}^{2}z}{\mathbb{d}t^{2}}} = {{{Fm}\left( {{I(t)},{z(t)}} \right)} + {{Fs}\left( {z(t)} \right)} + F_{friction}}} & (3)\end{matrix}$

where: I is coil current, R is coil resistance, z is stroke, E is chargevoltage, φ is total flux linkage of coil, Fm is electromagnetic force,Fs is pressure spring force, F friction is frictional force, and m isinertia mass Additionally, although the current flowing through thecoils is supplied from a constant voltage source according to theequations (1) (2) , the phenomenon herein can be treated in the samemanner also in the case of being supplied from a discharge circuit or acurrent application circuit such as capacitors as shown in FIG. 1.

Thus, the change in current waveform takes place when a circuit equationchanges from the equation (1) to the equation (2) at the moment of themoving part 6 changing from the state before being driven to the drivenstate, when a circuit equation changes from the equation (2) to theequation (1) at the moment of the moving part 6 changing from the drivenstate to after the completion of being driven, or in the case where anacceleration term d²z/dt² changes in a discontinuous manner due todiscontinuous change in mass m or load Fs in the motion equation of (3).These moments correspond to points at which a first-order differentialof a waveform, that is, current-time characteristics I (t), is zero, ora first-order differential or a second-order differential becomesdiscontinuous. In the description of the invention, points at whichcurrents change showing the above-mentioned phenomenon are genericallydefined as inflection points.

Meanwhile, in a theoretical viewpoint, waveforms of current flowingthrough the opening coil 14 can be obtained as described above. Examplesof being measured on an actual vacuum circuit breaker are now modeledand shown in FIG. 5 together with a stroke of the moving iron core 16.With reference to FIG. 5, a waveform of the current J flowing throughthe opening coil 14 comes to be the maximum value imax at a time ts of amotion start point (Act1) of the moving iron core 16, and comes to afirst infection point P at a time tp subsequently to the foregoing timets, and a second inflection point Q, being the minimum point at a timetq (hereinafter, it is referred to as a minimum point as well). Thetimes tp, tq are indicated establishing the instant of the opening coil14 being excited as a zero point (reference point) of time axis. Theother times hereinafter are indicated in the same manner. In addition, areference point of time may be set anywhere.

Strokes of the moving iron core 6 change as shown by a stroke st of FIG.5. The moving iron core 16 starts traveling at a time ts (point Act1 ofFIG. 5); the moving contact 5 b starts parting from the stationarycontact 5 a at a time tp, being a contact motion start time and anopening start time (time when the inflection point P takes place);thereafter the moving iron core 16 and the moving contact 5 b travel asan integral part; and they have traveled the entire stroke at a time tqcorresponding to the minimum point Q (time when the minimum point Qtakes place), and the moving iron core 16 and the moving contact 5 b arestopped, thus the opening being completed (opening completion point Act3of FIG. 5). That is, the time tq is a contact motion completion time,and an opening completion time. As described above, obtaining the timestp and tq when the inflection point P and the minimum point Q take placefocusing on waveforms of a current J flowing through the opening coil14, those obtained times are an opening start time and an openingcompletion time.

Now, described are the current measuring instrument 32 that measures thecurrent flowing through the opening coil 14, i.e., the current flowingthrough the connection line 31 when a vacuum circuit breaker is open,and the contact wear measuring device 33. A current flowing through theconnection line 31 is converted into a voltage output of analog signalsproportional to a current flowing through the current measuringinstrument 32, supplied to the AD converter 33 a, and converted todigital signals. In accordance with these digital signals, the time tpwhen the inflection point P of the current waveform of FIG. 5 ispositioned, that is, the inflection point P take place is obtained.Then, by measuring how times tp changes with respect to the time tp(initial) in the initial state of a vacuum circuit breaker, a wearamount of contact can be obtained by contact wear calculation means 33d.

A method of searching positions of the inflection point P is hereinafterdescribed. Herein, positions of the inflection point P means positionson coordinates when times are plotted along the axis of abscissas, andcurrents are plotted along the axis of ordinates. Although a variety ofmethods can be thought as the method for searching positions of theinflection point P, the method of focusing the rate of change in currentis described in this first embodiment. This searching is executed byopening start point search means 33 b. A storage region G of N numbersin size has been secured in the memory 33 a in order to be capable ofpreliminarily holding data of a time period necessary for opening of thevacuum circuit breaker. For example, supposing that a sufficient timeperiod needed for opening is 30 msec, when a quantization bit number is10 bits and a sampling rate is 100 kS/s (Δtg=10 μsec interval) like theabove-mentioned example, a storage region of N=3000 numbers in size with10 bits per one) is acquired as an array G.

Furthermore, a storage region, for example, of M=N/10 numbers in sizenecessary for the following operation processing is acquired as an arrayF. The opening start point search means 33 b executes processing in thefollowing procedure after having prepared the arrays in the memory 33 cas described above. Hereinafter, operations of the opening start pointsearch means 33 b and the contact wear calculation means 33 d aredescribed with reference to a flowchart of FIG. 7.

1) Fetching Current Value (Step S11)

Letting a time t when a vacuum circuit breaker receives an openingcommand 0, fetching currents flowing through the connection line 31 viathe current measuring instrument 32 is started at intervals of a timeΔtg (10 μsec), current values are converted to digital data with the ADconverter 33 a, and the data are stored in the array G of the memory 33c. A value at a time j·Δtg is stored in j-th element of the array G.Then, fetching is ended at a point of time of having obtained N numbersof data.

2) Smoothing (Step S12)

An average value of, e.g., ten numbers of data having been fetched isstored in an array F (Step S12). By smoothing, noise components, whichthe data having been stored in the array G possess, are reduced.Whereby, sampling data having been smoothed at intervals of Δtf=100 μseccan be obtained. Accordingly, a value at a time t=i·Δtf is stored ini-th element of the array F.

3) Searching Opening Start Time (Step S13)

Inflection point search means 33 b first obtains the maximum value ofdata in the array F. Next, the rates of change in current (dI/dt) areobtained in sequence. Values having been obtained in such a way areindicated in FIG. 8. As shown in FIG. 8, (dI/dt) sharply increases inthe beginning, passes a zero point U while decreasing by degrees fromthis point, and comes to be a negative value. This zero point Ucorresponds to a time ts at which a current J becomes the maximum valueimax in FIG. 5(a) being a motion start point of the moving iron core 16.Subsequently, after the time ts, (dI/dt) comes to be a negative value,continues to decrease, and then sharply increases at a point R. Thispoint R corresponds to the inflection point P, and a time tp when thisopening start point R takes place is a contact motion start time.

Additionally, in the foregoing description of the present invention, apoint, which corresponds to a point of a first-order differential ofcurrent-time characteristics I (t) being zero, or a first-order orsecond-order differential of current-time characteristics I(t) beingdiscontinuous, and at which current changes in the above-mentionedphenomenon, is generically defined as an inflection point. To determineparticularly this “coming to be discontinuous”, it is necessary to takethe following contents into consideration.

That is, the presence of this discontinuity is determined in the case ofmaking a determination assuming that no statistical error is included.Specifically, for example, there are some cases where results areobtained by smoothing processing of data having been actually measured,or by fitting with functions being divided for single or plural regions.In the case of making the smoothing processing, sharply-changed portionsdue to discontinuity of original data is subjected to “smoothing”, sothat the state as it is will not correspond to that “first-orderdifferential or second-order differential comes to be discontinuous”. Inthis case, however, positions of a “discontinuous” point can be judgedby estimating portions at which values of first-order differential orsecond-order differential with regard to the change in data in a certaintime period range. Thus, at least according to this invention, the casesas described above are also included in “points of coming to bediscontinuous” that are described in, e.g., claim 2. Furthermore, alsoin the case of fitting with a single function (although it is normallydifficult, so that it will be fitting with a plurality of functions),there is no “discontinuity of first-order differential or second-orderdifferential” in the proper sense of the word. However, the sameinterpretation as in the case of the above-mentioned smoothing is made.

4) Calculating a Wipe of Moving Contact (Step S14)

Contact wear calculation means 33 d first calculates a wipe Lw of themoving contact 5 b with a time difference Δtw(=tp−ts) between a time tp,being a contact motion start time, and a time ts, being a moving ironcore motion start time when the moving iron core 16 starts traveling.The relation of values between a time difference Δtw and a wipe Lw ismeasured with an actual device to create a database. A wipe Lw isobtained referring to this database.

In addition, a wipe is a distance that the moving iron core travels froma time point when the moving contact has started traveling up to a timepoint when a contact starts traveling, or is a difference betweencompression of spring in the closed state and compression of spring inthe opening state, and amount of change in wipe is equal to wear amountof contact.

5) Calculating Wear Amount of Contact (Step S15)

Furthermore, contact wear calculation means 33 d obtains a differenceΔLw between a current wipe Lw, being at the second predetermined time,and a wipe Lw0 when the contact shows no wear, having been measuredbefore at the first predetermined time, and determines a wear amount ofcontact from a difference between wipes.

6) Checking Wear Amount of Contact (Step S16)

Contact wear determination means 33 e checks whether or not a wearamount of contact having been determined exceeds a predetermined value.

7) External Outputting of Signals (Step S17)

Contact wear determination means 33 e externally outputs an alarm signaland a wear amount of contact in case of a wear amount of contactexceeding a predetermined value, and externally outputs a wear amount ofcontact in case of not exceeding a predetermined value.

As described above, wear amount of contact wears is obtained. Currentsflowing through the opening coil 14 before the contact shows no wear andafter it shows some wear are compared, which is shown in FIG. 9. Withreference to FIG. 9, solid line indicates a current J of the openingcoil 14 before the contact being worn, and broken line indicates acurrent of the opening coil 14 after the contact being worn. Withreference to FIG. 9, at the time of a new contact (at the firstpredetermined time according to the invention), a wipe ΔLw1 is obtainedwith a time difference between a time ts that corresponds to the maximumvalue imax of currents flowing through the opening coil 14 and a timetp1 that corresponds to the inflection point P. Further, at a point oftime more subsequent to the time of being new (at the secondpredetermined time according to the invention), a position where theinflection point P takes place shifts to the upper left of FIG. 9 as thewear of contact increases, and the inflection point P changes from atime tp1 to a time tp2. That is, a time period from the start of openingoperation of the moving iron core 16 to the beginning of parting of themoving contact 5 b from the stationary contact 5 a becomes shorter.Further, as shown in FIG. 9, a time of opening completion when themoving iron core 16 has reached a stroke end is changed from tq1 to tq2,resulting in a longer time period. The reason for this event is that amovement distance of a moving part comes to be longer by a distance dueto increase in wear amount of contact.

At this time, with a time difference Δt2 between a time ts thatcorresponds to the maximum value imax of currents flowing through theopening coil 14 (it is hardly changed even at the time of a contactbeing worn) and a time tp2 that corresponds to the inflection point Pand, a wipe Lw2 is obtained (Δt2=tp2−ts). Then, by the calculation witha difference ΔLW between the wipe Lw1 before the contact being worn andthe above-mentioned wipe Lw2, or with a data table representing therelation between a difference between wipes ΔLw and a wear amount ofcontact, a wear amount of contact is obtained.

In the above description, an example is described in which a wipe of themoving contact 5 b is obtained with a difference between a time ts and atime tp, and a wear amount of contact is obtained in accordance with thechange in wipe (changing from Δlw1 to Δlw2) . It is, however, alsopossible to obtain a wear amount of contact with the change in time tp(changing from tp1 to tp2), omitting the obtaining of wipe.

As described above, it is possible to obtain a position of theinflection point P in waveform of a current J of the opening coil 14 bythe opening start point search means 33 b, and to obtain a wear amountof contact in accordance with the change in position of the inflectionpoint P (the change of time in inflection point P taking place).Therefore, it becomes possible to measure wear amount of contact withoutuse of any optical detector, thus enabling a device to be downsized byeliminating the need of optical adjustment. In addition, although a wearamount of contact is obtained using current waveforms of an opening coilat the time of opening according to this first embodiment, it is alsopossible to obtain a wear amount of contact using current waveforms of aclosing coil 13.

Embodiment 2

In the foregoing first embodiment with reference to FIG. 5, a point atwhich a current value comes to be the maximum is a motion start point ofa moving iron core. As far as no strict accuracy is required, thisprocessing has no problem. However, in the case where the phenomenonshould be analyzed in more detail, an actual motion start point of themoving iron core comes to be a little before the maximum point ofcurrent in relation to a time constant of the circuit. An inflectionpoint thereof is generally hard to extract due to the small rate ofchange. According to this second embodiment, a simple method ofsearching an inflection point of in such a case is disclosed.

That is, as shown in FIG. 10, the moving iron core starts moving at apoint of time A′ before a point A, being the maximum point of current.In detail, although the inflection point of a current waveform ispresent at the point A′, the change in waveform is small as comparedwith that at point A corresponding to the extreme value easy to detect.Accordingly, to detect this change, it is necessary to carry out currentmeasurement with high accuracy, thus leading to high cost of a measuringdevice.

Then, the compensation of Point A is made with the use of a compensationtime period ΔT, being a compensation amount from A point to point A′,thereby enabling to calculate a more accurate state factor, being adriving parameter.

In general, there are some cases where an inflection point can bepresumed at higher speed, or more easily by the method of estimating aninflection point using a compensation time period ΔT from the minimumpoint or the maximum point in the vicinity than by the method ofcalculating a certain inflection point with waveform analysis.

In addition, calculation methods of a compensation time period ΔTinclude: the method of using a fixed value having been actually measuredpreliminarily, or having been determined by calculation preliminarily;the method of calculation with functions having been obtainedpreliminarily by experiment or calculation of the correlation between atime, current, and voltage value at point A, or the method ofcalculating from a map data; or the method of obtaining by creating anapproximate function from waveform data before at point A, and comparingthis approximate function with an actual waveform.

Embodiment 3

FIGS. 11 and 12 show another embodiment according to the invention. FIG.11 is a schematic diagram of a switching time period monitoring deviceof a vacuum circuit breaker. FIG. 12 is a flowchart showing operations.With reference to FIG. 11, an opening time period monitoring device 43acting as a state grasp device includes the same AD converter 33 a andmemory 33 cas those of FIG. 5, as well as opening-time minimum pointsearch means 43 a and closing-time minimum search means 43 b acting as asecond inflection point search means, and error determination means 43 cacting as signal transmission means.

Now, operation of the switching time period monitoring device 43 isdescribed referring to a flowchart of FIG. 12. An opening command switch28 is pressed to provide an opening command to an opening coil 14 tocause the opening coil 14 to perform an opening operation (Step S21). Atthis time, a current flowing through the connection line 31 is convertedinto a digital data with the AD converter 33 a to be fetched in thememory 33 c (Step S22). Thereafter, a smoothing processing is made inthe same manner as in the foregoing first embodiment (Step S23). Thesame minimum point Q as that shown in FIG. 5 is searched by opening-timeminimum point search means 43 a (Step S24).

The search of the minimum point Q is performed based on, for example,the rate of change in current J at the time of opening (di/dt). FIG. 8is a characteristic chart indicating the rate of change of a currentflowing through the opening coil 14 as shown before. With reference toFIG. 8, the minimum point at the time of opening (the minimum point Q ofFIG. 5) is searched by focusing the fact that (di/dt) is changed to benot less than a predetermined value in a positive direction at anopening completion point S that corresponds to the minimum point Q. Atime tq when this minimum point Q takes place is a movement completiontime that is an opening completion time, so that it is determined byerror determination means 43 c whether or not a time period tq is withina predetermined range (Step S25). In the case of being out of apredetermined range, an error signal indicating the error is transmitted(Step S26). In the case of being within a predetermined range, theprogram proceeds to Step S31.

A waveform of current flowing through the closing coil 13 at the time ofclosing is changed in the same manner as a current J shown in FIG. 5.Accordingly, it is possible to search the minimum point at the time ofclosing in the same manner as in search of the minimum point at the timeof opening. That is, a closing command switch 27 is pressed to provide aclosing command to the closing coil 13 thereby causing the closing coil13 to make a closing operation (Step S31). At this time, a currentflowing through the connection line 31 is converted into a digital datawith the AD converter 33 a to be fetched in the memory 33 c (Step S32).Thereafter, a smoothing processing is performed (Step S33). The sameminimum point as that shown in FIG. 5 is searched by closing-timeminimum point search means 43 b (Step S34). The search of the minimumpoint is performed in the same manner as in the foregoing Step S24. Atime when this minimum point takes place is a movement completion timeof the moving contact 5 b, that is, a closing completion time, so thatit is determined by error determination means 43 c whether or not aclosing completion time period is within a predetermined range (StepS35). In the case of being out of a predetermined range, an error signalindicating the error is transmitted (Step S36).

In the case of an abnormally long time period until the completion ofopening or closing, there may be any error such as increase infrictional resistance when the moving constant 5 b or the moving ironcore 16 travels. Furthermore, in the case where opening or closing hasnot completed, there maybe any movement failure of, e.g., the movingcontact 5 b or the moving iron core.

As described above, it is possible to detect the completion of openingor closing without use of a mechanical switching auxiliary contact bymonitoring an opening completion time period or a closing completiontime period serving as a contact movement completion time period by theerror determination means. In addition, it is possible to detect errorof driving states such as imperfect turning-on or impossible opening ofa breaker, thus enabling to contribute to the prevention of malfunctionor to the improvement in reliability.

Embodiment 4

FIG. 13 is a schematic diagram of a characteristic amount-measuringdevice of a vacuum circuit breaker showing a further embodimentaccording to the invention. With reference to FIG. 13, a characteristicamount-measuring device 53 acting as a state grasp device includesopening time period calculation means 53 a acting as characteristicamount grasp means and error determination means 53 b acting as signaltransmission means in addition to the same AD converter 33 and contactwear calculation means 33 d as those in FIG. 4, and the sameopening-time minimum point search means 43 a as that in FIG. 11. Adifference ΔLw between a current wipe Lw2 at the second predeterminedtime and a wipe Lw1 having been measured before at the firstpredetermined time is obtained by the same method as in theabove-mentioned first embodiment with the use of AD converter 33 a andcontact wear calculation means 33 d. A wear amount of contact isdetermined based on the difference ΔLw between the wipes. Further, aposition of the minimum point Q (it is also an inflection point) atwhich currents comes to be the minimum after the inflection point Pshown in FIG. 5 is obtained with opening-time minimum point search means43 a.

Opening time period calculation means 53 a obtains a time difference Δtdbetween a time tp and a time tq (tp and tq are shown in FIG. 5) from atime tp that corresponds to the inflection point P and a time tq thatcorresponds to the minimum point Q. Further, with this time differenceΔtd, an opening time period is obtained using an opening time perioddatabase in which the relation between a time difference and an openingtime period having been preliminarily measured with an actual device isstored in a table form. Error determination means 53 b determineswhether or not a wear amount of the contact or an opening time periodhaving been obtained as described above exceeds a predetermined value.In the case of exceeding a predetermined value, this error determinationmeans 53 b externally outputs an alarm signal, and a wear amount ofcontact or an opening time period having exceeded predetermined value.In the case of not exceeding a predetermined value, the errordetermination means 53 b externally outputs a wear amount of contact andan opening time period. In addition, it is preferable that opening timeperiod calculation means 53 a further makes a conversion of an openingtime period having been obtained to obtain an opening velocity.

Furthermore, this time difference Δtd becomes larger as a frictionalresistance when the moving contact 5 b or the moving iron core 16travels is increased. Accordingly, it is possible to obtain operatingconditions of the vacuum circuit breaker by obtaining the change in thetime difference Δtd.

Since it is possible to obtain the change in opening time period basedon the positions of the inflection point P and the minimum point Q of acurrent waveform of the opening coil by such a method, it becomespossible to make a device downsized and inexpensive by eliminating theneed of optical adjustment. Furthermore, since there is provided errordetermination means 53 b that determines whether or not a wear amount ofcontact or an opening time period is out of a predetermined range andtransmits an alarm in the case of error, it is possible to monitoroperation failure such as error in a wear amount of contact, orimperfect turning-on or impossible opening of a vacuum circuit breaker,thus enabling to achieve the improvement in reliability.

Embodiment 5

FIG. 14 is a schematic diagram of a characteristic amount-measuringdevice of a vacuum circuit breaker showing a further embodimentaccording to the invention. With reference to FIG. 14, characteristicamount-measuring device 63 acting as a state grasp device includescontact wear calculation means 63 a acting as contact wear grasp means.According to this embodiment, contact wear calculation means 63 aobtains a wear amount of contact by the method different from that bythe contact wear calculation means 33 d shown in FIG. 13. The otherarrangement is the same as that according to the third embodiment shownin FIG. 13, so that same reference numerals designate like parts, andfurther descriptions thereof are omitted. A position of the inflectionpoint P of a current waveform is obtained by the same method as thataccording to the above-mentioned first embodiment. Further, the minimumpoint Q at which currents comes to be the minimum after the inflectionpoint P shown in FIG. 5 is obtained with the minimum point search means53 a.

Opening time period calculation means 53 a obtains a time difference Δtdbetween a time tp that corresponds to the inflection point P, and a timetq that corresponds to the minimum point Q (=tq-tp, refer to FIG. 5).Further, with this time difference Δtd, an opening time period isobtained using an opening time period database in which the relationbetween a time difference Δtd and an opening time period having beenpreliminarily measured with an actual device is stored in a table form.Contact wear calculation means 63 a obtains a difference between a timedifference Δtd1 (=tq1−tp1, refer to FIG. 9) at the time of a newcontact, being the first predetermined time having been preliminarilymeasured with an actual device, and a current time difference Δtd2(=tq2−tp2, refer to FIG. 9) at the second predetermined time (after apredetermined number of switching has performed); and this contact wearcalculation means 63 a obtains a wear amount of contact from thedatabase representing the relation between the foregoing difference andthe wear amount of contact. Error determination means 53 b determineswhether or not a wear of the contact or an opening time period exceeds apredetermined value. In the case of exceeding a predetermined value,this error determination means 53 b externally outputs an alarm signal,and a wear amount of contact or an opening time period having exceeded apredetermined value. In the case of not exceeding a predetermined value,the error determination means 53 b externally outputs a wear amount ofcontact and an opening time period. In addition, it is preferable thatopening time period calculation means 53 a further makes a conversion ofan opening time period. having been obtained to obtain an openingvelocity. Furthermore, instead of obtaining a wear amount of contactfrom the change in time difference Δtd between a time tp and a time tq(the change from Δtd1 to Δtd2), it is preferable to obtain a wear amountof contact from the change in time tq, i.e., a difference between a timetq at the time of a new contact and a time tq2 after a predeterminednumber of switching has done.

As described above, it is possible to obtain a wear amount of contactfrom the change in time tp that corresponds to the inflection point P ofa current waveform of an opening coil and in time tq that correspond tothe minimum point Q thereof; or it is possible to obtain a wear amountof contact from the change in time tq that corresponds to the minimumpoint Q. Further, it is possible to obtain the change of an opening timeperiod from a time tp that corresponds to the inflection point P of acurrent waveform of the opening coil and time tq that corresponds to theminimum point Q thereof. Thus, it becomes possible to make a devicedownsized and inexpensive by eliminating the need of optical adjustment.Furthermore, since there is provided error determination means 53 b andthis error determination means 53 b determines whether or not a wearamount of contact or an opening time period is out of a predeterminedrange and generates an alarm in the case of error, it is possible toknow operation failure such as error in wear amount of contact,imperfect turning-on or impossible opening of a vacuum circuit breaker,thus enabling to achieve the improvement in reliability.

Embodiment 6

FIG. 15 is a schematic diagram of a switching control device of a vacuumcircuit breaker showing a further embodiment according to thisinvention. With reference to FIG. 15, the switching control device 73includes temperature/capacitor voltage obtaining means 73 a, closingtime period prediction means 73 b, and switching-on timing control means73 c. The remaining arrangement is the same as that shown in FIG. 4.First, the same inflection point P as shown in FIG. 5 is searched, and atime tp when an inflection point takes place is obtained by inflectionpoint search means 33 b. Contact wear calculation means 33 d calculatesa wipe Lw of the moving contact 5 b in the same manner as in the firstembodiment based on the time ts when currents flowing through theopening coil 14 comes to be the maximum and the above-mentioned time tp,and obtains a wear amount of contact based on a difference from a wipeLw0 before the contact being worn having been preliminarily calculated.Temperature/capacitor voltage obtaining means 73 a obtains dataregarding a temperature of the vacuum circuit breaker and a voltage ofthe closing capacitor 23. Closing time prediction means 73 b predictsand operates a closing time period at the time of next closing inaccordance with these temperature and voltage, and the above-mentionedwear amount of contact.

The closing time period, which the closing time period prediction means73 b predicts and operates, comes to be longer due to the fact that aresistance of the closing coil 13 is large in the case of the closingcoil 13 being at a high temperature, so that a flowing current becomessmaller. In case of the capacitor 23 being at a high temperature, acapacity of the capacitor 23 becomes larger, and the current flowingthrough the closing coil 13 becomes larger, so that the foregoingclosing time period comes to be shorter. In the case of a high chargevoltage of the capacitor 23, the current flowing through the closingcoil 13 becomes larger, so that the closing time period comes to beshorter. In addition, an internal part of a vacuum circuit breaker or apower switching apparatus including the vacuum circuit breaker can beexpected to be at a substantially uniform temperature, so thattemperature information at a certain point in the internal part of thepower switching apparatus can represent a temperature of the capacitor23 and the closing coil 13.

Furthermore, when the inflection point P shifts to the left and anopening start time comes to be earlier due to a wear of contact, themoving contact 5 b has to travel by an extra distance corresponding tothe wear amount of contact, and a movement time period that is anopening time period becomes longer by this distance. Therefore, also atthe time of closing, a movement distance of the moving contact 5 bbecomes longer by a distance for the wear amount of contact (refer totimes tp1, tp2 of FIG. 9), so that a closing time period is predicted byadding a time period of moving a distance for this wear amount ofcontact at the time of closing. Closing timing control means 73 ccontrols a switching-on (closing) timing of a vacuum circuit breaker onthe basis of a closing time period having been operated. Theswitching-on timing is controlled so that, for example, a rush currentflowing through the switching contacts may be nearly zero when thevacuum circuit breaker is switched on, thus achieving the reduction inwear amount of contact of a vacuum circuit breaker.

In addition, it is preferable that the predictive operation of a closingtime period is made with either of information about a voltage of theclosing capacitor 23 or of information about a temperature of theclosing coil 13 depending on a required accuracy. This predictiveoperation can be made also in the later-described seventh embodiment.

Embodiment 7

FIG. 16 is a schematic diagram of a switching control device of a vacuumcircuit breaker showing a further embodiment according to the invention.With reference to FIG. 16, a switching control device 83 includesopening-time minimum point search means 43 a and closing time periodprediction means 83 a. The other arrangement is the same as that shownin FIG. 15. First, the inflection point P and the minimum point Q (referto P, Q of FIG. 5) are searched by inflection point search means 33 band opening-time minimum point search means 43 a, and times tp, tq,being opening start and opening completion times when the inflectionpoint P and the minimum point Q take place respectively, are obtained. Amovement distance d of the moving contact 5 b at the time of opening isobtained from a difference Δtpq between the time tq and time tp.Temperature/capacitor voltage obtaining means 73 a obtains dataregarding a temperature of the vacuum circuit breaker and a voltage ofthe closing capacitor 23. Closing time prediction means 83 a predictsand operates a closing time period at the time of closing next inaccordance with the temperature and voltage, and the above-mentionedmovement distance d at the time of opening.

The closing time period, which the closing time period prediction means83 a predicts and operates, comes to be longer due to the fact that aresistance of the closing coil 13 is large in the case of the closingcoil 13 being at a high temperature, so that a flowing current becomessmaller. In case of the capacitor 23 being at a high temperature, acapacity of the capacitor 23 becomes larger, and the current flowingthrough the closing coil 13 becomes larger, so that the foregoingclosing time period comes to be shorter. In the case of a high chargevoltage of the capacitor 23, the current flowing through the closingcoil 13 becomes larger, so that the closing time period comes to beshorter. In addition, an internal part of a vacuum circuit breaker or apower switching apparatus including the vacuum circuit breaker can beexpected to be at a substantially uniform temperature, so thattemperature information at a certain point in the internal part of thepower switching apparatus can represent a temperature of the capacitor23 and the closing coil 13.

Furthermore, a movement distance of the moving contact 5 b at the timeof opening extends due to wear of contact, so that also a closing timeperiod comes to be longer by this distance. A table representing therelation between a movement distance d and a closing time period, inwhich both are associated, has been preliminarily prepared. Whenpredicting a closing time period, the closing time period is obtainedwith reference to this table. Closing timing control means 73 c controlsa switching-on (closing) timing of a vacuum circuit breaker on the basisof a closing time period having been operated.

Embodiment 8

According to the foregoing first embodiment, the search of eachinflection point on a current waveform is carried out on the basis ofthe rate of change over time of current (FIG. 8). On the other hand,according to this eighth embodiment, a current waveform is representedby an approximate curve of polynomial. Operations of the case ofsearching each inflection point on the basis of such approximate curveare hereinafter described referring to a flowchart of FIG. 17.

1) Fetching Current Value (Step S41)

Letting a time t when a vacuum circuit breaker receives an openingcommand 0, fetching currents flowing through the connection line 31 viathe current measuring instrument 32 is started at intervals of a timeΔtg (10 μsec), current values are converted into digital data with theAD converter 33 a, and the data are stored in an array G of the memory33 c. A value at a time j·Δtg is stored in j-th element of the array G.Then, fetching is ended at a point of time of having obtained N numbersof data.

2) Smoothing (Step S42)

An average value of, e.g., ten numbers of data having been fetched isstored in an array F (Step S42). By smoothing, noise components, whichthe data having been stored in the array G possess, are reduced. Thus,sampling data having been smoothed at intervals of Δtf=100 μsec can beobtained. Accordingly, a value at a time t=i·Δtf is stored in i-thelement of the array F.

3) Maximum Value Searching (Step S43)

An element number imax that provides the maximum value of an array F isobtained.

4) Setting Inflection Point Near-Point Search Start Point (Step S44)

An element number, for example, 30 numbers that correspond to 3 msecbefore imax is set to be an inflection point near-point search startpoint ist.

5) Obtaining Approximate Curve with Respect to Array F (Step S45)

Approximation is made with a polynomial using a least square withrespect to values of the array F in a range from ist to imax. Forexample, a quadratic curve (at²+bt+c) is made to be approximate, andcoefficients a, b, c are obtained respectively (refer to FIG. 18). Theapproximation by the least square is generally a well-known way, so thatthe detailed description is omitted. Although an approximation is notlimited to a quadratic, a quadratic curve is easy to process.

6) Determining Whether or Not Approximation is Successful (Step S46)

It is determined whether or not the approximation is successful withsigns of a coefficient a. That is, as shown in FIG. 19, supposing thata≧0, an approximate curve has a convex shape downward, so that it isfailure. In the case of the failure, 1 is added to ist, and the programreturns to Step S45. On the other hand, in the case of a<0, anapproximate curve has a convex shape upward, so that the approximationis successful. At this time, a value of imax is set to be anapproximation end point ied (imax=ied).

7) Obtaining Extrapolation Error (Step S47)

An error D=F(t)−(at²+bt+c) is obtained with respect to an extrapolationpoint t=ied+1.

8) Determining Whether or Not it is a Near-Point of an Inflection Point(Step S48)

Whether or not it is a near-point of an inflection point is determineddepending on whether or not an error D exceeds a decision value havingbeen preliminarily determined. On the supposition it is a near-point ofan inflection point, it will be a value of not more than a decisionvalue.

Then, for example, letting a decision value 5, on the supposition of D≧5as shown in FIG. 20, it is not a near-point of an inflection point, andthe program proceeds to the subsequent Step S19. On the supposition ofD>5 as shown in FIG. 21, it is a near-point of an inflection point, andthe program proceeds to Step S50.

9) Recalculation of Approximate Curve (Step S49)

1 is added to a value of ied. A quadratic curve (at2+bt+c) is madeapproximate using a least square again with respect to values of anarray F in a range from ist to ied, and coefficients a, b, c areobtained respectively. Then, the program returns to Step S47, and theprocess from Step S47 to Step S49 is repeated until a near-point of theinflection point is obtained.

10) Setting Inflection Point Search Start Point (Step S50)

An element number of an array G that corresponds to a point thatreturns, for example, 100 μsec from the near-point of the inflectionpoint is set to be an inflection point search start point jst. That is,jst=10×(ied−1)

12) Setting Inflection Point Search End Point (Step S51)

An element number of an array G that corresponds to a point, forexample, 200 μsec ahead from the near-point of the inflection point isset to be an inflection point search end point jed. That is,jed=10×(ied+2)

13) Obtaining Approximate Curve (Step S52)

Approximation is made with a polynomial using a least square withrespect to values of the array G in a range from jst to jed. Forexample, a quadratic curve (at²+bt+c) is made approximate, andcoefficients a, b, c are obtained respectively.

14) Determining Inflection Point (Step S53)

As shown in FIG. 22, tp=−b/(2 a) that provides the minimum value of aquadratic curve (at²+bt+c) is set to be a position of the inflectionpoint P. Further, with reference to FIG. 22, Dn, Dn+1, Dn+2, Dn+3indicated by black dots are data in the array G.

15) Calculating Time Difference in Inflection Point Positions (Step S54)

A time difference (tp0−tp) between a time tp that corresponds to aposition of an inflection point P1 having been searched in such amanner, and a time tp0 that corresponds to a position of an inflectionpoint at the time of the contact not being worn, having beenpreliminarily measured, is obtained.

15) Calculating Wear Amount of Contact (Step S55)

Contact wear calculation means 33 d obtains a wear amount of contactfrom an expression or table of the relation between the time difference(tp0−tp) and a wear amount of contact (almost in proportion) having beenpreliminarily obtained by the experiment or calculation.

In the procedure as described above, it is possible to obtain a positionof an inflection point of a current waveform of the opening coil usingthe approximation by a least square, and to obtain a wear amount ofcontact from the position of the inflection point P (time tp when theinflection point P takes place). Accordingly, it becomes possible tomeasure a wear amount of contact without use of any optical detector,thus enabling to make a device downsized by eliminating the need ofoptical adjustment. Contact wear measuring device 33 can be put intopractice just with an one-chip IC, thus making it suitable to beintegrated in a vacuum circuit breaker which is particularly required toachieve reduction in size and weight, and reduction in cost.

Moreover, an inflection point P or Q can be obtained not only byinflection point search means, minimum point search means or the like,but can be obtained by the following method. For example, a waveform Jof currents, shown in FIG. 5, is displayed on a screen of a display;inflection points P and Q are clicked with a mouse by visually observingthis display screen; times tp and tq are obtained from address pointshaving been clicked; and a wear amount of contact is automaticallycalculated from the same database of wear amount of contacts as thatused in the first embodiment.

Embodiment 9

Several methods of detection on the basis of current waveform aredescribed in each of the foregoing embodiments. In the case, however, ofan opening or closing coil that are excited by an electric charge ofcapacitors, an inflection point of this voltage similar to that ofcurrent appears. Accordingly, conditions of device such as wear amountof contact, opening time period or closing time period can be obtainedby the same method. According to this ninth embodiment, a characteristicamount is obtained with an inflection point of this voltage waveform.FIG. 23 shows results of measuring voltages to be induced to anon-excitation coil, i.e., the closing coil 13 at the time of openingoperation (indicated by a narrow line), and corresponds to FIG. 5showing a current waveform. Further, in the drawing, a thick solid lineshows a stroke of the moving iron core 16.

With reference to FIG. 23, an inflection point P of a voltage waveformhaving been obtained can be obtained, for example, based on timedifferential characteristics thereof, and an opening start time (contactmotion start time) tp can be obtained. Accordingly, it comes to bepossible to grasp the change in characteristic amounts of a powerswitching apparatus by the same method as described above in the case ofusing a current waveform.

Embodiment 10

According to the heretofore embodiments, change information at points ofinflection of a current waveform from a movement start point to amovement completion point of a moving iron core (corresponding to anopening completion point Q in the example of FIG. 15) is a target. It isdescribed in this tenth embodiment that change information can beobtained from a waveform after movement completion of the moving ironcore.

With reference to FIG. 24, a current waveform after completion of theoperation, that is on and after Q point, being a point of time ofmovement completion of the moving iron core represents a waveform inwhich change in current caused by bouncing at the time of impact of amoving part of the electromagnetic operating mechanism is superposedFurther, a magnitude of this mechanical bouncing reflects conditionssuch as driving velocity or fixed state of the power switchingapparatus. Thus, it is possible to detect the change in state of anapparatus from the change in current waveform on and after this Q point.

Specifically, a current waveform in the case of no bouncing, with theuse of specified plural points, is estimated from a current waveform onand after Q point, and a differential between this estimated currentwaveform (it is indicated by an interpolated curve including a dottedpart of FIG. 24) and an actually measured waveform (indicated with asolid line) is obtained. This differential waveform, shown in the lowerhalf of FIG. 24, represents a magnitude of the above-mentionedmechanical bouncing. Numerical values such as maximum value, time widthof a waveform or integral value thereof are extracted from thisdifferential waveform. These numerical values are compared with data atthe normal time or limit values having been preliminarily determined,thereby making the state determination of a power switching apparatus.In the case where any error is determined, an error signal is outputted.It is possible to preliminarily know an error state of the apparatus byadding such error determination means.

Embodiment 11

In addition, although a vacuum circuit breaker is taken as an example ofa power switching apparatus, it is a matter of course to apply thisinvention to a power switching apparatus including the similarlyarranged electromagnetic operating mechanism such as air break switch orelectromagnetic contactor. Furthermore, this invention is applicable towider range of apparatus.

FIG. 25 shows the eleventh embodiment of the invention, in which a stategrasp device according to the invention is applied to an electromagneticoperating mechanism to drive a brake apparatus for use in, e.g.,elevator. In the drawing, the electromagnetic mechanism 100 is the onesimilar to the electromagnetic mechanism 10 described with reference toFIGS. 1, 3, a moving iron core 103 drives a connection part 104 in acrosswise direction of a page space by operating currents flowingthrough a pair of coils 101, 102. FIG. 25 shows a state of brakeapparatus being operated, in which a brake lever 106 sandwiches a rail107 by a constant force due to tension of a release spring 105,resulting in generation of braking force.

When current is supplied to coils 101, 102 to be excited, the movingiron core 103 travels to the left of page space, and causes the brakelever 106 to turn while pressing the release spring 105. The brake lever106 comes to separate from the rail 107, resulting in release of thebraking force. Thus, an elevator cage starts moving.

FIG. 26 shows a coil current waveform of the brake apparatus of FIG. 25.With reference to FIG. 26, an inflection point P subsequent to the timepoint of current peak is a brake release operation completion time.Furthermore, when, e.g., friction at the connection part is increasedowing to deterioration with the passage of time and the mechanism stateis changed, a current value is increased as shown in the drawing. Theinflection point shifts in order of P1→P2→P3, a brake release operationcompletion time period becomes longer.

Accordingly, in the same manner as described in the foregoing firstembodiment and the like, the change with the passage of time in timeinformation regarding the inflection point is grasped and monitored byinflection point search means of a current waveform, therebytransmitting an error alarm before occurrence of operation failure. Inthis manner, it is possible to prevent occurrence of fault, as well asto reliably carry out maintenance.

As a matter of course, also the change in friction at the brake-slidingportion exerts effects on time information regarding the inflectionpoint having been searched, so that it is possible to estimate afriction from the data of inflection point.

Further, the invention is not limited to a brake apparatus of anelevator, but is likewise applicable to a valve gear that makesswitching operation of valves for use in an automobile, bringing aboutthe same advantages.

Furthermore, generally, the invention is likewise applicable to stategrasp of an electromagnetic operating system of which drivingcharacteristics are changed due to change in state factor such asfriction, etc., of an operated apparatus that is driven by theelectromagnetic operating system, or state grasp of the operatedapparatus operated by the electromagnetic operating system.

Additionally, in some fields of a state grasp device according to thisinvention being applied, only one coil of an electromagnetic operatingmechanism thereof is used. In such a device, to search an inflectionpoint from a voltage waveform, it is necessary to measure a voltage ofthis coil during being supplied with current from a drive power supplysuch as capacitors. In this case, the change in voltage drop that occursin internal resistance of the above-mentioned drive power supply due tochange in current will be a voltage change waveform, being a searchtarget.

Embodiment 12

A manner of simply detecting a capacity change of the capacitor actingas a drive power supply of an electromagnetic operating mechanism (seeFIG. 1) is hereinafter described. That is, generally in a capacitor,elements are deteriorated in the process of repeating the operations ofcharge and discharge, and an electrostatic capacity thereof decreases bydegrees. When a capacity of the capacitor is decreased below a certainlevel, the current ensuring a normal driving operation cannot besupplied to coils, resulting in operation failure of the electromagneticoperating system. Consequently, it becomes necessary to monitor acapacity.

FIG. 27 shows a voltage waveform of a terminal voltage of the capacitorat the time of discharge to coils. Furthermore, an attention isparticularly focused on the change in voltage waveform in the case wherea capacity of the capacitor is changed. That is, as shown in thedrawing, when a capacity of the capacitor is decreased from an initialstate (100%) to 80%, 60%, an attenuating velocity of voltage is found tochange. Therefore, by detecting such attenuation of voltage after apredetermined time period has passed from the instant of voltageapplication, capacity deterioration of the capacitor can be grasped.Supposing that an alarm is transmitted when detecting a predeterminedcapacity decrease, it is possible to prevent the electromagneticoperating system from occurrence of failure, as well as it is possibleto reliably carry out the maintenance.

In particular, on the supposition that this capacity change detectionmeans is integrated into a switching control device according the sixthand seventh embodiments (refer to FIGS. 15, 16), it is possible tomonitor a capacity of the capacitor without use of any dedicatedcapacity monitor, thus enabling to arrange a control deviceinexpensively.

Embodiment 13

A manner of simply detecting an ambient temperature of anelectromagnetic operating system is hereinafter described. An extremelyweak current is applied to a closing coil 13 or an opening coil 14 of anelectromagnetic operating system at a predetermined time when a breakeris in no operation, and output voltage therefrom is measured. Note thata resistance of, e.g., conductor for use in coils linearly changes withrespect to a temperature. Accordingly, a resistance of the coil has beenpreliminarily measured, and the rate of change in resistance relative tothe above-mentioned resistance is measured, thereby enabling tobasically grasp an ambient temperature. Since an output voltage in thecase where an extremely weak current flows changes in accordance withV=I*R at the time of a resistance being changed, the ambient temperaturechange can be detected by monitoring the above-mentioned output voltage.

Thus, an error alarm is transmitted before the occurrence of operationfailure of a breaker in accordance with an ambient temperature havingbeen detected, whereby it is possible to prevent occurrence of anyfault, as well as to reliably carry out the maintenance. Furthermore,supposing that a temperature having been estimated is fetched in theswitching control device according to the sixth and seventh embodiments(refer to FIGS. 15, 16), it is possible to monitor an ambienttemperature without use of any dedicated thermometer, thus enabling toarrange an inexpensive control device.

In addition, although opening/closing coils of the electromagneticoperating mechanism 10 are used herein, it is also preferable to use,for example, a small coil winding for measuring temperature. Thiswinding is not necessarily required to be integrated in theelectromagnetic operating mechanism 10.

Embodiment 14

In this embodiment, a further manner of simply detecting an ambienttemperature of an electromagnetic operating system is described.

FIG. 28 shows an example of estimating an ambient temperature using aHall element. With reference to FIG. 28, a magnetic flux monitoring holeis formed in a part of a stationary iron core, a Hall element 110 ismounted on this monitoring hole. In general, an output voltage from theHall element has a constant gradient with respect to an ambienttemperature. That is, Vh=K·α·B (where: Vh is a Hall element outputvoltage, K is a temperature coefficient, α is an output sensitivity atan ordinary temperature, and B is a magnetic flux density). In the casewhere the electromagnetic operating mechanism 10 holds an opening orclosing state and a permanent magnet generates a constant magneticfield, the change in Hall element output voltage Vh will show only inthe form of a temperature change based on the above-mentionedtemperature coefficient k. That is, it comes to be possible to estimatean ambient temperature by monitoring the change in Vh.

Thus, an error alarm is transmitted before the occurrence of operationfailure of a breaker in accordance with an ambient temperature havingbeen detected, whereby it is possible to prevent occurrence of anyfault, as well as to reliably carry out the maintenance. Furthermore,supposing that a temperature having been estimated is fetched in theswitching control device according to the sixth and seventh embodiments(refer to FIGS. 15, 16), it is possible to monitor an ambienttemperature without use of a dedicated thermometer, thus enabling toarrange an inexpensive control device.

In addition, although a Hall element is located on the peripheral sideof an electromagnetic operating mechanism, this layout position can beanywhere only on condition that it is on the way of path where magneticfluxes of the permanent magnet 16 a pass through.

Embodiment 15

In this embodiment, a state grasp device capable of simply implementingthe operation for obtaining current value information or voltage valueinformation at inflection point, is described.

FIG. 29 is a view showing an operation processing section according to afifteenth embodiment of the invention. With reference to FIG. 29, thereare provided first-order differential waveform detection means 124 fordetecting a first-order differential waveform of the current flowingthrough an opening coil 121, and zero·cross detection means 127 fordetecting a zero·cross point of this differential waveform andoutputting a pulse signal at the zero·cross point.

With reference to FIG. 30, points of being an extremely large value andan extremely small value out of inflection points on a current waveformof this FIG. 30(a) are replaced with zero·cross points on a currentfirst-order differential waveform (FIG. 30(b)). With reference to FIG.29, current signal conversion means 126A fetches a pulse signal from thezero·cross detection means 127 as a trigger signal, fetches a currentvalue of the opening coil 121 from the current waveform detection means122 as current change information at these inflection points, anddelivers them to characteristic amount measuring device 125.

Voltage signal conversion means 126B fetches a pulse signal from thezero·cross detection means 127 as a trigger signal, fetches a voltagevalue of the opening coil 121 from the voltage waveform detection means123 as voltage change information at these inflection points, anddelivers them to the characteristic amount measuring device 125.

According to such arrangement, since points of inflection on a currentwaveform are extracted as a plurality of pulse signals by the zero crossdetection means 127, it is unnecessary to fetch all waveforms of currentand voltage. Only measured values obtained by reading a pulse signal asa trigger signal by ADC have to be processed in an operating unit.Consequently, it is possible to achieve the reduction in load of theoperating unit, and the device arrangement at low cost.

Further, a current differential waveform can be detected with awire-wound CT. However, since a current waveform of a generalelectromagnetic operating mechanism includes much signals of a frequencyband in the vicinity of 10 Hz, an accurate measurement cannot beperformed due to influence of saturation of a core of a normalwire-wound CT equipped with core. A more accurate measurement can becarryout by using an air-core CT (the so-called Rogowski CT).

As shown in FIG. 29, it is preferable that there is provided an ORcircuit 129, whereby a pulse signal corresponding to a specified time,which is generated at a timer unit 128 with reference to a driving startcommand signal is added as a pulse signal to be used as a triggersignal.

Furthermore, it is preferable that a voltage detected value or a voltagedifferential detected value may be the target of zero·cross detectionother than a current detected value.

As shown in FIG. 30(c), it is preferable to add a circuit acting to letelectric signals from first-order differential waveform detection means124 further into a differential circuit to fetch out a second-orderdifferential signal of current, and to execute peak detection orzero·cross detection of the second-order differential signal. Peak valueor zero·cross point of current second-order differential signalrepresents inflection point of current signal, so that the search of awider range of inflection points and the operation and obtaining ofchange information at these inflection points can be simply andinexpensively carried out.

Embodiment 16

FIG. 31 is a schematic diagram showing a state grasp device according toa sixteenth embodiment of the invention. This sixteenth embodiment hasan object of simply making the operation of obtaining change informationin the same manner as in the foregoing fifteenth embodiment.

With reference to FIG. 31, the fact that there are provided first-orderdifferential waveform detection means 124 for detecting a first-orderdifferential waveform of current through the opening coil 121, andzero·cross detection means 127 for detecting zero·cross points of thisdifferential waveform and outputting a pulse signal at these zero·crosspoints is the same as in the foregoing first embodiment.

On the other hand, signals that are output from the voltage waveformdetection means 123 are inputted to the threshold detection means 130.Only pulse signals from these threshold detection means 130 andzero·cross detection means 127 are inputted to an operating unit of thecharacteristic amount measuring device 125.

The threshold detection means 130, as shown in FIG. 32, outputs signalsof which output pulse signal is ON as long as input signals are signalslarger than a constant threshold. Thus, information about a pulse widthtime period at this time includes information about an attenuationwaveform of voltage. It is possible to use this pulse width informationas one of measured values for calculating state factors of a device.

An operating unit of the characteristic amount-measuring device 125calculates a state factor of the power switching apparatus based on timeinformation of each pulse signal from threshold detection means 130 andzero·cross detection means 127.

In addition, it is preferable to take signals from current waveformdetection means 122 as inputs of threshold detection means 130.

By employing such arrangement, it is possible to omit an ADC section,thus enabling to arrange an operating unit at less cost.

Embodiment 17

According to each of the foregoing embodiments, described are means andmethods for detecting specified states, for example, a contact motionstart time or a contact movement completion time, and further acharacteristic amount such as wear amount of a switching contact basedon a variation over time thereof with information indicated byinflection points on an output waveform provided from measurement meansof current or voltage. In the foregoing description, these means andmethods are confirmed to be further useful as compared with theconventional means and methods.

Meanwhile, the present invention, that is a state grasp device thatobtains change information at inflection points on an output waveformprovided from measurement means for measuring current flowing through anelectromagnetic coil or voltage generated at an electromagnetic coil,and that estimates a state of an operated apparatus or anelectromagnetic operating system on the basis of these changeinformation, is effective as means for grasping a still wider range ofstates other than in the embodiments having been specificallyexemplified heretofore. However, in the actual application thereof, itis necessary to take notice of the following points.

That is, change information, being time information, current valueinformation, and voltage value information at each inflection point aregenerally affected by plural kinds of states, that is, by the change ina plurality of state factors. Accordingly, to grasp a state quantity ofthese plurality of state factors in an appropriate manner and with highaccuracy, not only the analysis of phenomenon in the case whererespective state factors are made to change as a matter of course isneeded, but also analysis of complex phenomenon caused by the pluralityof factors is further needed.

According to this seventeenth embodiment, although a part of descriptionis overlapped with the foregoing descriptions, various useful methodsare described from the above-mentioned viewpoint. Although a powerswitching apparatus is presumed and described as an operated apparatus,it is a matter of course that this seventeenth embodiment is likewiseapplicable to the other devices such as brake apparatus having beenadopted in the eleventh embodiment.

FIG. 33 shows current and voltage of an opening coil at the time ofopening. A charge voltage of the capacitor is used as a driving powersupply. A current waveform or voltage waveform of the coil repeats acomplicated variation from the start of coil current-carrying to theoperation completion of a moving part or after the operation completion,and possesses complicated inflection points of as indicated by A to H inthe drawing. Further, in the drawing, a point I indicates as an examplea feature time point to be described in the later-described eighteenthembodiment. Ways of these inflection points appearing are differentdepending on opening/closing operation or types of electromagneticoperating system. A current waveform and a voltage waveform are fetchedin the switching control device by current waveform detection means andvoltage waveform detection means. Subsequently, inflection points in awaveform are extracted using an analysis algorithm from these waveformdata to let times corresponding to these points Ta-Th, current valuesIa-Ih, and voltage values Va-Vh.

These measured values are varied depending on a state of the powerswitching apparatus. Herein, a state of the power switching apparatus isa value of factors causing operation characteristics of the powerswitching apparatus to change. Due to the fact that a variation of thesefactors exceeds a predetermined value, any operation fault of the powerswitching apparatus occurs, or the probability of occurring anyoperation fault rises These state factors can be changed depending onoperation history of the power switching apparatus or with lapse oftime. Specifically, the state factors include a temperature of the powerswitching apparatus, a frictional force generated at a moving part, acapacity of the capacitor and a charge voltage of the capacitor insystem of carrying current through coils using the capacitor, a powersupply voltage in system of carrying current through coils using aconstant voltage power supply, a resistance value in a coilcurrent-carrying circuit, a wear mount of switching constants in avacuum valve, and a holding power of opening or closing with a permanentmagnet.

FIG. 34 shows an example of a coil current waveform at the time ofopening of a power switching apparatus in the normal state, and a coilcurrent waveform in the power switching apparatus in which the frictionof a driving part is increased. In this example, an electromagnetic coilis driven by a discharge current from the capacitor. When a frictionalforce that is generated at the moving part is increased, a spring forceexerting on the moving iron core and a part of electromagnetic forcecounteracts the friction, resulting in reduction in force of driving themoving iron core, and the reduction in movement velocity of the movingiron core. Therefore, a time period from the start of movement of themoving iron core to the start of a switching contact being parted, and atime period from the start of movement of the moving iron core to thecompletion of operation of the moving iron core come to be longer. Thatis, times Tb, Tf at inflection points B, F are delayed. Further, since amovement speed of the moving iron core at a time point B when theswitching contact begins to part becomes smaller as compared with thatat the normal time, a counter electromotive voltage that is generated atcoils in accordance with a movement speed of the moving iron core, andcurrent is more likely to flow. Accordingly, a current value Ib at aninflection point B tends to be larger as compared with that at thenormal time.

Further, at a point F of operation completion of the moving part, acurrent value If is increased due to decrease in velocity of the movingiron core. Moreover, due to the fact that a driving time period comes tobe longer, an electric charge having been discharged from the capacitoruntil an inflection point F is reached is increased, and a voltage valueVf at the inflection point F is decreased, whereby a current value If isdecreased. Since this effect is added, the change different from thechange in current value at the inflection point B is shown at theinflection point F. Values of time, current or voltage are likewisechanged in accordance with a frictional force at the other inflectionpoints.

FIG. 35 shows an example of a coil current waveform at the time ofopening of the power switching apparatus in the normal state, and a coilcurrent waveform in the power switching apparatus of a switching contactbeing worn. In this example, an electromagnetic coil is driven by adischarge current from the capacitor. When the switching contact isworn, a distance, which the moving iron core travels, from a motionstart point A of the moving iron core to a point B of the switchingcontact begins to part becomes shorter. Therefore, a time Tb at thepoint B comes to be a smaller value than that at the normal time.Furthermore, a distance, which the moving iron core travels, from themotion start point A of the moving iron core to the point B of theswitching contact begins to part is understood to be a compression of aspring. Since a compression of the spring becomes smaller, a velocity ofthe moving iron core at the inflection point B comes to be smaller ascompared with that at the normal time. Accordingly, a counterelectromotive voltage that is generated at the coil is decreased inaccordance with a movement speed of the moving iron core, and current ismore likely to flow. Thus, a current value Ib at the inflection point Btends to be larger as compared with that at the normal time. Further, atthe operation completion point F of the moving iron core, the time Tb atthe inflection point F becomes larger due to decrease in velocity of themoving iron core. Furthermore, with respect to the increase effect of acurrent value If due to the decrease in velocity of the moving ironcore, an electric charge to be discharged from a capacitor until theinflection point F is reached is increased due to the longer drivingtime period, and a voltage value Vf at the inflection point F isdecreased, whereby a current value If is decreased. Accordingly, thecurrent value If at the inflection point B tends to decrease as comparedwith that at the normal time. Furthermore, values of a time, current, orvoltage are changed in accordance with a wear amount of contact likewisein the other inflection points.

FIG. 36 shows an example of a coil current waveform at the time ofopening of a power switching apparatus in the normal state, and a coilcurrent waveform in the power switching apparatus which capacity isdecreased due to deterioration of a capacitor. In this example, anelectromagnetic coil is driven by a discharge current from thecapacitor. When a capacity of the capacitor is decreased, the decreasein capacitor voltage due to the discharge of current to the coil comesto be larger than that at the normal time. Therefore, current values ateach inflection point are decreased. On the other hand, since time ateach inflection point depends on a velocity of the moving iron core tobe determined mainly by a spring force, there is no much difference fromthose at the normal time.

As described above, the time, current value, and voltage value at eachinflection point are reflected on each state of the power switchingapparatus at each individual point of time. For example, a current valueIb at the inflection point B is changed in accordance with the change ineach state factor such as wear amount of contact, frictional force ofthe moving part, capacitor deterioration, and has such a correlation asshown in FIGS. 37 (a) to (c). However, in the case where the influenceof the change in not less than two state factors is reflected on acurrent value Ib, it is difficult to separately estimate the changes innot less than two state factors only based on Ib FIGS. 37 (d) to (f)show the influence of the change in each state factor such as wearamount of contact, frictional force of the moving part, a capacitordeterioration on a current value If at the inflection point F. Thechange tendency due to the change in each state factor of a currentvalue If at the inflection point F is different from the change of valueIb. It can be said that Ib and If have independent change tendencieswith respect to three state factors. As a matter of course, currentmeasured values Ib, If at the above-mentioned inflection points B, F arechanged depending upon the change in state factors other than. a wearamount of contact, a frictional force of the moving part, and acapacitor deterioration.

In general, in the case where there are M numbers of measured values of,e.g., time, current, or voltage having an independent change tendencywith respect to N numbers of state factors, on the supposition of M≧N,it is possible to numerically estimate a variation of N numbers of statefactors by first-order approximation from M numbers of measured values.Further, in the case of the presence of a higher-order correlation inthe correlation between a state factor and a quantity to be measured, alarger number of independent measured values are needed.

Further, generally, it is necessary that measurement accuracy of thesemeasured values is equal to or below a required sensitivity of ameasured value corresponding to a sensitivity required for calculating avariation in state factors. It is possible, however, to achieve highermeasurement accuracy by averaging a plurality of measured values. Thus,by adding any non-independent measured value of higher measurementaccuracy to the above-mentioned independent measured values, it ispossible to improve the accuracy in estimating any state factorvariation.

Calculation methods of a variation of state factors include a method ofhaving preliminarily prepared a correlation map between a measured valueand a state factor, and calculating a variation of a state factor byinterpolation or extrapolation from an actually measured value; or amethod of having preliminarily determined a function with which a statefactor is directly derived from a measured value. Means for determiningthese correlation map (database) or function include the method ofdetermination on the basis of actually measured data, the method ofdetermination on the basis of analysis simulation, and the method ofdetermination using both of them.

State factors are numerically calculated, and thereafter these statefactors are compared with limit values having been preliminarilydetermined, thereby enabling to determine error of a power switchingapparatus. In the case where states are determined to be in error, anerror signal is outputted, thus enabling to preliminarily detect afault.

In addition, there are some state factors to be varied depending ontemperature conditions of the power switching apparatus. For example, acapacity of a general capacitor is decreased due to reduction intemperature, and a resistance value of a coil is decreased due toreduction in temperature. As described above, to divide the change ofstate factors into that due to the deterioration and that due totemperature variation, temperatures are measured using temperaturemeasuring means, and an estimated value of a variation of state factorsare compensated, thereby enabling to carry out more accurate estimationof state factors.

Further, supposing that state factors of the power switching apparatuscan be numerically obtained, it is possible to predict operation of thepower switching apparatus with the use of these state factors. Theprediction of operation is to numerically predict driving parameterssuch as driving velocity or closing time period at the time of nextclosing operation base on a variation in state factors at the time ofopening operation, or to numerically predict driving parameters such asdriving velocity or opening time period at the time of next openingoperation based on a variation in state factors at the time of closingoperation.

The prediction methods of driving parameters of the power switchingapparatus include the method of having preliminarily created acorrelation map between state factors and drive parameters, or themethod of having preliminarily prepared functions to derive drivingparameter from state factors. Further, there is also a method ofcalculating drive parameters using a correlation map or functions frommeasured values of time, current value, voltage value, and temperatureat points of inflection.

Embodiment 18

According to each of the foregoing embodiments, change information isobtained from inflection points on an output waveform from measurementmeans of current or voltage. However, the inventors have found thefollowing fact as a result of carrying out extensively variousexperiments concerning state grasp of devices. The fact is thatinformation useful for state grasp can be obtained from current valueinformation or voltage value information at a time point of feature,being a point of time after a predetermined time period has passed sincethe moment of starting the excitation of an electromagnetic coil. Inaddition, this feature time point is not limited to the above-describedexcitation start time point, but points of time when a predeterminedtime period has passed from the time points where points of inflectionhaving been described in the foregoing embodiments are positioned, canbe targeted.

According to this eighteenth embodiment, described is a method ofestimating and grasping states from change information at this featuretime point, or how timing of this feature time points is set.

With reference to the mentioned FIG. 33, a point at which a time periodTx has passed since the discharge start, is set to be a feature timepoint I. At this time, Tx is a time period interval that is determinedso that the change in current value or voltage value is larger withrespect to the change of specified state factors, and so that the changein current value and voltage value is smaller with respect to the otherstate factors. FIG. 38 shows situations of the change in coil voltagewaveform with respect to the change in each state factor of (a) wearamount of contact, (b) friction, (c) capacitor capacity, and (d)capacitor charge voltage.

For example, in the vicinity of Tx=0.035, the change in current value issmall with respect to the change in three state factors of contact wear,friction, and charge voltage; and the change in voltage value is largewith respect to the change in capacitor capacity. Further, a voltagevalue at a point o Tx=0 comes under only the influence of the change incharge voltage. In case of using measured values at such a feature timepoint, a variation of a specified factor can be separated from the otherstate factors, and calculated.

As an example of the specific calculation method of a time periodinterval Tx, there are the following methods. In the case of N numbersof state factors being present, letting the permitted minimum value of astate factor R, being one state factor thereof Rmin and the permittedmaximum value of the state factor Rmax, the minimum value, which avoltage value V takes, is VRmin and the maximum value is VRmax when astate factor R is made to change from Rmin to Rmax. Also as to statefactors Ti I=1, . . . , N−1) other than the state factor R, when lettingthe maximum value and the minimum value of a voltage value VTi_min,VTi_max in the case where values of each state factor is changed fromthe permitted minimum value to the permitted maximum value,s1=|VRmax−VRmins2=Σ|VTi_max−VTi_min|,

it is preferable to obtain as Tx such a point that s1 becomes largerthan a certain value A having been preliminarily set on the basis ofmeasurement error, and that s2 becomes smaller than a certain value Bhaving been preliminarily set to be smaller than the mentioned value A.Herein, although Tx is obtained with respect to a voltage value, it isalso preferable to obtain Tx with respect to a current value.

Furthermore, it is preferable to obtain as Tx such a appoint that S1>A,s2<B, as well as s1 is the maximum.

In addition, it is preferable to obtain such a time period Tx that s1>A,s2<B, as well as d=s2/s1 is the minimum. Further, it is also preferableto select such a plurality of Tx that d is extremely small other than apoint of d being the minimum. Moreover, it is preferable that thecalculation method of s1 and s2 ares1=(VRmax−VRmin)²s2=Σ(Vi_max−Vi_min)²

Furthermore, it is preferable that the calculation method of d isd=s2−s1.

It is also preferable that a selection range of Tx includes a timeperiod after the driving completion of an electromagnetic operatingsystem, in addition to a time period from the start of carrying a coilcurrent to the driving completion of the electromagnetic operatingsystem.

Furthermore, although the method of separating the change in one statefactor from the other state factors is described in the above-mentionedexample, it is preferable to be used as the method of separating thechange in a plurality of state factors from the change in otherplurality of state factors.

For example, in the case of N numbers of state factors being present, N,N=M+L, numbers of state factors are divided into M numbers of statefactors Ri (i=1, . . . , M) and L numbers of state factors Tj (j=1, . .. , L). When letting the minimum value and the maximum value of voltagevalues VRi_max, VRi_min, VTj_max, VTj_min in the case where a value ofeach state factor is changed from the permitted minimum value to thepermitted maximum value,s1=ΣVRi_max−VRi_min|,s2=ΣVTj_max−VTj_min|,it is preferable to obtain as Tx a point at which s1 is larger than avalue A and s2 is smaller than a value B. Although Tx is obtained withrespect to a voltage value, it is preferable to obtain Tx with respectto a current value.

Further, it is preferable to obtain as Tx a point at which s1>A, s2<B,as well as s1 is the maximum.

It is also preferable to obtain such a time period Tx that s1>A, s2<B,as well as d=s2/s1 is the minimum. Further, it is preferable to selectsuch a plurality of Tx that d is extremely small other than a point of dbeing the minimum. It is also preferable that the calculation method ofs1 and s2 ares1=Σ(VRi_max−VRi_min)²s2=Σ(VTj_max−VTj_min)²Furthermore, it is preferable that the calculation method of d isd=s2−s1. It is preferable that a selection range of Tx includes a timeperiod after the driving completion of an electromagnetic operatingsystem, in addition to a time period from the start of carrying a coilcurrent to the driving completion of the electromagnetic operatingsystem.

By this method, a variation in a specified state factor cannot beestimated based on voltage value or current value. However, by makingthe combination of measured values of voltage or current at a pluralityof feature time points having been obtained by this method, a variationof a specified state factor can be estimated. Further, it is preferablethat measured values to be combined are values measured at theabove-mentioned inflection points.

Furthermore, in the case of N numbers of state factors being present, N(N=M+N) numbers of state factors are divided into M numbers of statefactors Ri (i=1, . . . , M) and L numbers of state factors Tj (j=1, . .. , L).

There is a yet further method of obtaining Tx. By this method, takingrespective state factors Ri (i=1, . . . , M) as one group, and lettingthe minimum of voltage values VRmin and the maximum of voltage valuesVRmax in the case. where values of state factors that are included in agroup thereof are changed from respective permitted minimum values torespective permitted maximum values;

taking respective state factors Ti (j=1, . . . , L) as one group, andletting the minimum of voltage values VTmin and the maximum of voltagevalues VTmax in the case where values of state factors that are includedin a group thereof are changed from respective permitted minimum valuesto respective permitted maximum values; ands1=|VRmax−VRmins2=|VTmax−VTmin|a point at which s1 becomes larger than a value A and s2 becomes smallerthan a value B is obtained as Tx. Although, Tx is obtained with respectto a voltage value, it is also preferable to obtain TX with respect to acurrent value.

Further, it is preferable to obtain as Tx a point at which s1>A, s2<B,as well as s1 is the maximum.

It is also preferable to obtain such a time period Tx that s1>A, s2<B,as well as d=s2/s1 is the minimum. Further, it is preferable to selectsuch a plurality of Tx that d is extremely small other than a point of dbeing the minimum.

It is also preferable that the calculation method of s1 and s2 ares1=Σ(VRi_max−VRi_min)²s2=Σ(VTj _(—max−) VTj_min)²Furthermore, it is preferable that the calculation method of d isd=s2−s1. It is preferable that a selection range of Tx includes a timeperiod after the driving completion of an electromagnetic operatingsystem, in addition to a time period from the start of carrying a coilcurrent to the driving completion of the electromagnetic operatingsystem.

By this method, a variation of a specified state factor cannot beestimated based on voltage value or current value. However, by makingthe combination of measured values of voltage or current at a pluralityof feature time points having been obtained by this method, a variationin a specified state factor can be estimated. Moreover, it is preferablethat measured values to be combined are values measured at theabove-mentioned inflection points.

As the method of causing values of a state factor included in a group ofone state factor to change from each permitted minimum value to eachpermitted maximum value, there are a method of continuously changingvalues, and a method of discontinuously changing values at intervals.Further, as a procedure of causing values of a state factor included ina group of one state factor to change from each permitted minimum valueto each permitted maximum value, there are a procedure of causing eachstate factor to change at a constant rate all at once, and a procedureof causing values of one state factor at a time to change in sequence insuch a manner that a value of the first state factor is changed from theminimum to the maximum and subsequently a value of the second statefactor is changed from the minimum to the maximum. In the case where Mnumbers of state factors are included in a group of one state factor,there is a further procedure of dividing values from the permittedminimum value to the permitted maximum value of respective state factorsinto k−1, and assaying all the combinations of k numbers of values ofrespective state factors included in a group of a state factor, of whichk numbers of values have been obtained by division.

By this method, a variation in a specified state factor cannot beestimated from voltage value or current value. However, by making thecombination of measured values of voltage or current at a plurality offeature time points having been obtained in a group of a different statefactor, a variation in a specified state factor can be estimated.Further, it is possible to estimate a variation in a specified statefactor by combining these measured values with measured values at theother feature time points or inflection points.

As described above, in the state grasp device according to theinvention, which is disposed in an electromagnetic operating system thatincludes a fixed iron core; a moving iron core constructed movably withrespect to this fixed iron core; and an electromagnetic coil that isexcited by a driving power supply, and causes the moving iron core totravel, thereby driving an operated apparatus that is connected to themoving iron core; the state grasp device comprises measurement means formeasuring a current flowing through the electromagnetic coil or avoltage to be generated at the electromagnetic coil, and search meansfor obtaining change information on an output waveform from thismeasurement means; and estimates a state of the operated apparatus orelectromagnetic operating system on the basis of change information fromthis search means. As a result, it is possible to estimate states of anoperated apparatus or an electromagnetic operating system with a devicethat needs no optical adjustment, as well as is inexpensive andsmall-sized.

Further, the search means thereof includes inflection point search meansfor searching an inflection point on output-time characteristics showingthe change with time of output values that are obtained from measurementmeans, and the search means obtains at least one kind of information outof time information, current value information and voltage valueinformation at the inflection point. As a result, it is possible toobtain useful change information from inflection points on output-timecharacteristics.

Furthermore, the inflection point search means thereof includes afunction to search a position of the other inflection point on the basisof a compensation amount having been preliminarily set from a positionof one inflection point. As a result, it becomes easy to search pointsof inflection.

Further, the inflection point search means thereof obtains a time whenan inflection point takes place on the basis of the rate of change withtime of the output-time characteristics. As a result, it is possible toeasily obtain times when inflection points take place.

Further, the inflection point search means thereof applies output-timecharacteristics to an approximate curve of polynomial, and obtains atime when an inflection point takes place on the basis of thisapproximate curve. As a result, it is possible to easily obtain timeswhen inflection points take place.

Further, the search means thereof obtains at least one kind ofinformation of current value information and voltage value informationat a feature time point, being a time point after a predetermined timeperiod has passed from at least one of a time point of starting theexcitation with the driving power supply and a time point when aninflection point is positioned on output-time characteristics showingthe change with time of output values that are obtained from measurementmeans as change information. As a result, it is possible to obtainuseful change information from a feature time point on output-timecharacteristics.

Further, with respect to each of a plurality of groups consisting of notless than one of state factors having been preliminarily set as to aplurality of state factors causing states of the operated apparatus orelectromagnetic operating system, on the basis of output-timecharacteristic information that can be obtained by causing statequantities of a state factor belonging to a group thereof to changewithin a predetermined range;

the search means thereof extracts a time zone in which change in outputdue to change in state quantity of the state factor on output-timecharacteristic information corresponding to a group of one state factoris larger than a value A having been preliminarily set on the basis of ameasurement error; as well as change in output due to change in statequantity of the state factor on output-time characteristic informationcorresponding to a group of at least one of the other state factors issmaller than a value B having been preliminarily set to be smaller thanthe above-mentioned value A, and selects at least one time point as afeature time point for each of these time zones having been extracted.As a result, it is possible to obtain useful feature time points.

Further, the electromagnetic operating system thereof drives a movingcontact of a switching contact of a power switching apparatus, being anoperated apparatus; and search means thereof includes at least one of afirst inflection point search means for obtaining, as a contact motionstart time, a time when a first inflection point that appearssubsequently to the maximum value of a current waveform provided fromcurrent measurement means takes place, and a second inflection pointsearch means for obtaining, as a contact movement completion time, atime when a second inflection point, which takes place after the contactmotion start time, and at which a current waveform becomes the minimum,takes place. As a result, it is possible to obtain a contact motionstart time or a contact movement completion time of a power switchingapparatus with a device that needs no optical adjustment, as well as isinexpensive and small-sized.

Further, there is provided characteristic amount grasp means forobtaining change in characteristic amount of the power switchingapparatus from a variation with time in at least one of a contact motionstart time and a contact movement completion time. As a result, it ispossible to obtain the change in various characteristic amounts with adevice that needs no optical adjustment, as well as is inexpensive andsmall-sized; and it is further possible to appropriately grasp a stateof the power switching apparatus.

Further, the electromagnetic coil thereof is an opening electromagneticcoil; first inflection point search means obtains, as a first contactmotion start time, a contact motion start time when the openingelectromagnetic coil is excited at a first predetermined time, as wellas obtains, as a second contact motion start time, a contact motionstart time when the opening electromagnetic coil is excited at a secondpredetermined time sequentially after the first predetermined time; andthe characteristic amount grasp means obtains a wear amount of theswitching contact as a characteristic amount on the basis of the firstand second contact motion start times. As a result, it is possible toobtain a wear amount of the switching contact with a device that needsno optical adjustment, as well as is inexpensive and small-sized.

Further, the electromagnetic coil thereof is an opening electromagneticcoil; second inflection point search means obtains, as a first contactmovement completion time, a contact movement completion time when theopening electromagnetic coil is excited at a first predetermined time,as well as obtains, as a second contact movement completion time, acontact movement completion time when the opening electromagnetic coilis excited at a second predetermined time sequentially after thementioned first predetermined time; and the mentioned characteristicamount grasp means obtains a wear of the switching contact as acharacteristic amount on the basis of the first and second contactmovement completion times. As a result, it is possible to obtain a wearamount of the switching contact with a device that needs no opticaladjustment, as well as is inexpensive and small-sized.

Further, the electromagnetic coil thereof is an opening electromagneticcoil, and includes both first inflection point search means and secondinflection point means; at the first predetermined time, the firstinflection point search means obtains, as the first contact motion starttime, a contact motion start time when the opening electromagnetic coilis excited, and the second inflection point search means obtains acontact movement completion time as the first contact movementcompletion time; at the second predetermined time sequentially after thementioned first predetermined time, the first inflection point searchmeans obtains, as the second contact motion start time, a contact motionstart time when the opening electromagnetic coil is excited, and thesecond inflection point search means obtains a contact movementcompletion time as the second contact movement completion time; andcharacteristic grasp means obtains a first time difference, being adifference between the first contact movement completion time and thefirst contact motion start time, as well as obtains a second timedifference, being a difference between the second contact movementcompletion time and the second contact motion start time, and obtains asa characteristic amount a wear amount of the switching contact on thebasis of the first and second time differences. As a result, it ispossible to obtain a wear amount of the switching contact with a devicethat needs no optical adjustment, as well as is inexpensive andsmall-sized.

Further, there are provided both first and second inflection pointsearch means; and the mentioned characteristic amount grasp meansobtains, as a characteristic amount, a movement time period of themoving contact on the basis of a contact motion start time and a contactmovement completion time. As a result, it is possible to obtain amovement time period of the moving contact with a device that needs nooptical adjustment, as well as is inexpensive and small-sized.

Further, the electromagnetic operating system thereof drives a movingcontact of a switching contact of a power switching apparatus, being anoperated apparatus, is provided with an opening electromagnetic coil anda closing electromagnetic coil to be excited with an electric chargehaving been charged in a capacitor; the search means thereof includes atleast one of the first inflection point search means obtaining, as acontact motion start time, a time when the first inflection point takesplace which point appears subsequently to the maximum value of a currentwaveform provided by current measurement means, and the secondinflection point search means obtaining, as a contact movementcompletion time, a time when the second inflection point, which takesplace subsequently to the contact motion start time, and at which acurrent waveform becomes the minimum, takes place; and there areprovided closing time period prediction means for predicting a closingcompletion time period when the closing electromagnetic coil is excitednext on the basis of at least one of a contact motion start time and acontact movement completion time, and at least one of a charge voltageof the capacitor and temperature information of the power switchingapparatus; and timing control means for controlling timing of excitingthe closing electromagnetic coil next on the basis of a closingcompletion prediction time period. As a result, it is possible to makean operating life of the switching contact longer.

Further, there is provided means for measuring a voltage of theelectromagnetic coil when a predetermined extremely weak current iscarried to the electromagnetic coil, obtaining coil resistance changecharacteristics of the electromagnetic coil from current voltage values,and obtaining temperature information of the closing electromagneticcoil on the basis of this coil resistance change characteristics. As aresult, it is possible to grasp an ambient temperature inexpensivelywithout provision of a dedicated thermometer.

Further, a Hall element is mounted on the iron core forming a magneticcircuit, and there is provided means for measuring voltage changecharacteristics of the Hall element under the conditions of constantmagnetic flux, and obtaining temperature information of the closingelectromagnetic coil on the basis of this voltage changecharacteristics. As a result, it is possible to gasp an ambienttemperature inexpensively without provision of a dedicated thermometer.

Further, at least one of an inflection point and a feature time pointcontains a point that is extracted on output-time characteristics afterthe movement completion of the moving iron core. As a result, it ispossible to cause a state after the movement completion of the movingiron core to be a grasp target.

Further, the search means thereof includes zero·cross detection meansfor differentiating a current flowing through the electromagnetic coilor a voltage generated at the electromagnetic coil, and for outputting apulse signal at a zero·cross point of differential output thereof; andobtains time information of an inflection point with a pulse signal. Asa result, it is possible to achieve reduction in operation load, andreduction in cost.

Further, there is provided operation means for operating at least onekind of variation in state quantity, a driving parameter, and aremaining operating life of the operated apparatus or electromagneticoperating system on the basis of at least one kind of information oftime information, current value information, and voltage valueinformation at the inflection point, and current value information andvoltage value information at a feature time point. As a result, it ispossible to grasp a wide variety of states of an operated apparatus andelectromagnetic operating system.

Further, there is provided signal transmission means for transmittingsignals when a change amount over time of the variation exceeds apredetermined value. As a result, it is possible to preliminarily detectdriving error; and it is possible to prevent occurrence of malfunctionof the operated apparatus and electromagnetic operating system,resulting in improvement in reliability.

INDUSTRIAL APPLICABILITY

A state grasp device according to the present invention is not onlyapplicable to a power switching apparatus such as vacuum circuitbreakers, but is widely applicable to an electromagnetic operatingsystem including a fixed iron core; a moving iron core constructedmovably with respect to this fixed iron core; and an electromagneticcoil that is excited by a driving power supply, and causes the movingiron core to travel, thereby driving an operated apparatus that isconnected to the moving iron core such as electromagnetic operatingmechanism to drive a brake apparatus for use in elevators, etc. Withthis state grasp device, it is possible to grasp various states of anoperated apparatus simply and inexpensively without use of complicatedand expensive optical means.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of a vacuum circuit breaker using anelectromagnetic operating mechanism according to a first preferredembodiment of the present invention.

FIG. 2 are state views each showing switching states of the vacuumcircuit breaker.

FIG. 3 is an enlarged view of an electromagnetic operating mechanism ofFIG. 1.

FIG. 4 is a schematic diagram showing an arrangement of a contactwear-measuring device of FIG. 1.

FIG. 5 is a characteristic chart showing a current flowing through anopening coil and a stroke of a moving iron core.

FIG. 6 is a characteristic chart showing a mass and a contact pressureof a contact at the time of operation of a vacuum circuit breaker.

FIG. 7 is a flowchart for explaining operation of the contact wearmeasuring device of FIG. 1.

FIG. 8 is a characteristic chart showing the rate of change in currentflowing through the opening coil.

FIG. 9 is an explanatory chart showing a waveform of current flowingthrough the opening coil and a stroke in comparison between at the timeof no wear of contact and at the time of some wear of the contact.

FIG. 10 is a chart explaining a manner of obtaining the other inflectionpoint A′ by compensation from the inflection point A according to asecond embodiment of the invention.

FIG. 11 is a schematic diagram of a switching time period monitoringdevice of a vacuum circuit breaker according to a third embodiment ofthe invention.

FIG. 12 is a flowchart for explaining operation of the switching timeperiod monitoring device of FIG. 11.

FIG. 13 is a schematic diagram of a characteristic amount measuringdevice of a vacuum circuit breaker according to a fourth embodiment ofthe invention.

FIG. 14 is a schematic diagram of a switching control device of a vacuumcircuit breaker according to a fifth embodiment of the invention.

FIG. 15 is a schematic diagram of a switching control device of a vacuumcircuit breaker according to a sixth embodiment of the invention.

FIG. 16 is a schematic diagram of a switching control device of a vacuumcircuit breaker according to a seventh embodiment of the invention.

FIG. 17 is a flowchart for explaining operation of a contactwear-measuring device of a vacuum circuit breaker according to an eighthembodiment of the invention.

FIG. 18 is an explanatory chart for explaining the operation of thecontact wear-measuring device.

FIG. 19 is an explanatory chart for explaining the operation of thecontact wear-measuring device.

FIG. 20 is an explanatory chart for explaining the operation of thecontact wear-measuring device.

FIG. 21 is an explanatory chart for explaining the operation of thecontact wear-measuring device.

FIG. 22 is an explanatory chart for explaining the operation of thecontact wear-measuring device.

FIG. 23 is a characteristic chart showing a voltage induced to a closingcoil and a stroke of a moving iron core according to a ninth embodimentof the invention.

FIG. 24 is a chart showing current characteristics after a time point ofthe operation completion of a power switching apparatus according to atenth embodiment of the invention.

FIG. 25 is a schematic view of a brake apparatus employing anelectromagnetic operating mechanism according to an eleventh embodimentof the invention.

FIG. 26 is a chart showing a waveform of current flowing through a coilof the brake apparatus.

FIG. 27 is a chart showing a voltage waveform in the case where acapacity of a capacitor of an electromagnetic operating mechanismaccording to a twelfth embodiment of the invention.

FIG. 28 is an enlarged view of an electromagnetic operating mechanism onwhich a Hall element is mounted according to a fourteenth embodiment ofthe invention.

FIG. 29 is a diagram showing an operational processing section accordingto a fifteenth embodiment of the invention.

FIG. 30 is a chart showing a correlation between a current waveform anda current differential waveform.

FIG. 31 is a diagram showing an operational processing section accordingto a sixteenth embodiment of the invention.

FIG. 32 is a chart showing a correlation between a voltage waveform andan output from threshold detection means.

FIG. 33 is a chart showing inflection points and feature time points oncurrent and voltage waveforms of an electromagnetic coil according to aseventeenth embodiment of the invention.

FIG. 34 is a chart showing coil current waveforms in the normal stateand in the state in which friction of a drive section is increased.

FIG. 35 is a chart showing coil current waveforms in the normal stateand in the state of a switching contact being worn.

FIG. 36 is a chart showing coil current waveforms in the normal stateand in the state in which a capacity of a capacitor is decreased due todeterioration thereof.

FIG. 37 are charts each showing a correlation between a current value Ibat the inflection point B and a current value If at the inflection pointF, shown in FIG. 33, and change in each state factor such as wear amountof contact, frictional force of the moving part and capacitordeterioration.

FIG. 38 are charts each showing a correlation between a coil voltagewaveform and change in each state factor such as wear amount of contact,frictional force of the moving part, capacitor deterioration anddecrease in charge voltage according to an eighteenth embodiment of theinvention.

DESCRIPTION OF REFERENCE NUMERALS

-   3: vacuum valve, 5: contact, 5 a: fixed contact, 5 b: moving    contact, 7: driving rod,-   10: electromagnetic operating mechanism, 13: closing coil, 14:    opening coil, 20: driving power supply, 23: closing capacitor, 24:    opening capacitor, 32: current measuring instrument,-   33: contact wear-measuring device, 33 b: opening start point search    means, 33 c: memory,-   33 d: contact wear-calculation means, 33 e: contact-wear    determination means, 43: switching time period monitoring device, 43    a: opening-time minimum search means, 43 b: closing-time minimum    search means-   43 c: error determination means, 53: characteristic amount measuring    device, 53 a: opening time period calculation means-   53 b: error determination means, 63: characteristic amount measuring    device, 63 a: contact wear calculation means,-   73: switching control device, 73 a: temperature/capacitor voltage    obtaining means-   73 b: closing time period prediction means, 73 c: switching-on    timing control means, 83: switching control device-   83 a: closing time period prediction means, 102, 102: coils, 103:    moving iron core-   104: connection part, 106: brake lever, 107: rail, 110: Hall element-   121: opening coil, 122: current waveform detection means,-   123: voltage waveform detection means-   124: first-order differential waveform detection means,-   125: characteristic amount measuring device-   126A: current signal conversion means, 126B: voltage signal    conversion means-   127: zero·cross detection means, 130: threshold detection means

1. A state grasp device, which is disposed in an electromagneticoperating system comprising a fixed iron core; a moving iron coreconstructed movably with respect to said fixed iron core; and anelectromagnetic coil that is excited by a driving power supply, andcauses said moving iron core to travel, thereby driving an operatedapparatus that is connected to said moving iron core, the state graspdevice comprising measurement means for measuring a current flowingthrough said electromagnetic coil or a voltage to be generated at saidelectromagnetic coil, and search means for obtaining change informationthat is changeable owing to determination with a passage of time inusing of said operated apparatus or said electromagnetic operatingsystem, on an output waveform from this measurement means; and estimatesa state of the operated apparatus or electromagnetic operating system onthe basis of change information from said search means.
 2. The stategrasp device according to claim 1, wherein said search means comprisesinflection point search means for searching an inflection point onoutput-time characteristics indicating a change with time of outputvalues that are obtained from said measurement means, and obtains atleast one kind of information out of time information, current valueinformation, and voltage value information at said inflection point. 3.The state grasp device according to claim 2, wherein said inflectionpoint search means includes a function to search a position of the otherinflection point on the basis of a compensation amount having beenpreliminarily set from a position of one inflection point.
 4. The stategrasp device according to claim 2, wherein said inflection point searchmeans obtains a time when said inflection point takes place on the basisof the rate of change with time of said output-time characteristics. 5.The state grasp device according to claim 2, wherein said inflectionpoint search means applies said output-time characteristics to anapproximate curve of a polynomial, and obtains a time when saidinflection point takes place on the basis of said approximate curve. 6.The state grasp device according to claim 1, wherein said search meansobtains, as said change information, at least one kind of information ofcurrent value information and voltage value information at a featuretime point, being a time point after a predetermined time period haspassed from at least one of a time point of starting the excitation withsaid driving power supply and a time point where an inflection point ispositioned on output-time characteristics showing the change with timeof output values that are obtained from said measurement means.
 7. Thestate grasp device according to claim 6, wherein with respect to each ofa plurality of groups consisting of not less than one of state factorshaving been preliminarily set as to a plurality of state factors causingstates of said operated apparatus or electromagnetic operating system,on the basis of said output-time characteristic information that can beobtained by causing state quantities of said state factor belonging to agroup thereof to change within a predetermined range; said search meansextracts a time zone in which the change in output due to change instate quantity of said state factor on said output-time characteristicinformation of a group of one state factor is larger than a value ahaving been preliminarily set on the basis of a measurement error; aswell as the change in output due to change in state quantity of saidstate factor on said output-time characteristic information of a groupof at least one of the other state factors is smaller than a value bhaving been preliminarily set to be smaller than said value a, andselects at least one time point as said feature time point for each ofthe time zones having been extracted.
 8. The state grasp of a powerswitching apparatus according to claim 8, wherein said electromagneticoperating system drives a moving contact of a switching contact of apower switching apparatus, being said operated apparatus, and comprisescurrent measurement means for measuring current flowing through saidelectromagnetic coil as said measurement means; and said search meanscomprises at least one of a first inflection point search means forobtaining, as a contact motion start time, a time when a firstinflection point that appears subsequently to the maximum value of acurrent waveform provided from said current measurement means takesplace, and a second inflection point search means for obtaining, as acontact movement completion time, a time when a second inflection point,which takes place after said contact motion start time and at which saidcurrent waveform becomes the minimum, takes place.
 9. The state graspdevice of a power switching apparatus according to claim 8, whereinthere is provided characteristic amount grasp means for obtaining thechange in characteristic amounts of said power switching apparatus froma variation with time of at least one of said contact motion start timeand said contact movement completion time.
 10. The state grasp device ofa power switching apparatus according to claim 9, wherein saidelectromagnetic coil is an opening electromagnetic coil; said firstinflection point search means obtains, as a first contact motion starttime, said contact motion start time when said opening electromagneticcoil is excited at a first predetermined time, as well as obtains, as asecond contact motion start time, said contact motion start time whensaid opening electromagnetic coil is excited at a second predeterminedtime sequentially after said first predetermined time; and saidcharacteristic amount grasp means obtains a wear amount of saidswitching contact as said characteristic amount on the basis of saidfirst and second contact motion start times.
 11. The state grasp deviceof a power switching apparatus according to claim 9, wherein saidelectromagnetic coil is an opening electromagnetic coil; said secondinflection point search means obtains, as a first contact movementcompletion time, said contact movement completion time when said openingelectromagnetic coil is excited at a first predetermined time, as wellas obtains, as a second contact movement completion time, said contactmovement completion time when said opening electromagnetic coil isexcited at a second predetermined time sequentially after said firstpredetermined time; and said characteristic amount grasp means obtains awear amount of said switching contact as said characteristic amount onthe basis of said first and second contact movement completion times.12. The state grasp device of a power switching apparatus according toclaim 9, wherein said electromagnetic coil is an opening electromagneticcoil, and comprises both said first inflection point search means andsaid second inflection point means; at the first predetermined time,said first inflection point search means obtains, as the first contactmotion start time, said contact motion start time when said openingelectromagnetic coil is excited, and said second inflection point searchmeans obtains said contact movement completion time as the first contactmovement completion time; at the second predetermined time sequentiallyafter said first predetermined time, said first inflection point searchmeans obtains, as the second contact motion start time, said contactmotion start time when said opening electromagnetic coil is excited, andsaid second inflection point search means obtains said contact movementcompletion time as the second contact movement completion time; and saidcharacteristic grasp means obtains a first time difference, being adifference between said first contact movement completion time and saidfirst contact motion start time, as well as obtains a second timedifference, being a difference between said second contact movementcompletion time and said second contact motion start time, and obtains,as said characteristic amount, a wear amount of said switching contacton the basis of said first and second time differences.
 13. The stategrasp device of a power switching apparatus according to claim 9,wherein there are provided both said first and second inflection pointsearch means; and said characteristic amount grasp means obtains, assaid characteristic amount, a movement time period of said movingcontact on the basis of said contact motion start time and said contactmovement completion time.
 14. A switching control device of a powerswitching apparatus employing the state grasp device according to claim2, wherein said electromagnetic operating system drives a moving contactof a switching contact of a power switching apparatus, being saidoperated apparatus, is provided with an opening electromagnetic coil anda closing electromagnetic coil to be excited with an electric chargehaving been charged in a capacitor as said electromagnetic coil, andcomprises current measurement means for measuring current flowingthrough said electromagnetic coil; wherein said search means comprisesat least one of the first inflection point search means obtaining, as acontact motion start time, a time when the first inflection point takesplace which point appears subsequently to the maximum value of a currentwaveform provided by said current measurement means, and the secondinflection point search means obtaining, as a contact movementcompletion time, a time when the second inflection point, which takesplace subsequently to said contact motion start time and at which saidcurrent waveform becomes the minimum, takes place; and wherein there areprovided closing time period prediction means for predicting a closingcompletion time period when said closing electromagnetic coil is excitednext on the basis of at least one of said contact motion start time andsaid contact movement completion time, and at least one of a chargevoltage of said capacitor and temperature information of said powerswitching apparatus; and timing control means for controlling timing ofexciting said closing electromagnetic coil next on the basis of saidclosing completion prediction time period.
 15. The switching controldevice of a power switching apparatus according to claim 14, whereinthere is provided means for measuring a voltage of said electromagneticcoil when a predetermined extremely weak current is carried to saidelectromagnetic coil, obtaining coil resistance change characteristicsof said electromagnetic coil from said current·voltage values, andobtaining temperature information of said closing electromagnetic coilon the basis of said coil resistance change characteristics.
 16. Theswitching control device of a power switching apparatus according toclaim 14, wherein a hall element is mounted on said iron core forming amagnetic circuit, and there is provided means for measuring voltagechange characteristics of said hall element under the conditions ofconstant magnetic flux, and obtaining temperature information of saidclosing electromagnetic coil on the basis of said voltage changecharacteristics.
 17. The state grasp device, wherein said inflectionpoint according to claim 2 contains a point that is extracted on saidoutput-time characteristics after the movement completion of said movingiron core.
 18. The state grasp device according to claim 2, wherein saidsearch means comprises zero·cross detection means for differentiating acurrent flowing through said electromagnetic coil or a voltage generatedat said electromagnetic coil, and for outputting a pulse signal at azero·cross point of a differential output thereof; and obtains timeinformation of an inflection point with said pulse signal.
 19. The stategrasp device provided with operation means for operating at least onekind of variation in state quantity, driving parameter, and remainingoperating life of said operated apparatus or electromagnetic operatingsystem on the basis of at least one kind of information of timeinformation, current value information, and voltage value information atsaid inflection point according to claim
 2. 20. The state grasp deviceaccording to claim 19, wherein there is provided signal transmissionmeans for transmitting signals when a change amount over time of saidvariation exceeds a predetermined value.
 21. The state grasp device,wherein said inflection point according to claim 3 contains a point thatis extracted on said output-time characteristics after the movementcompletion of said moving iron core.
 22. The state grasp device, whereinsaid feature time point according to claim 6 contains a point that isextracted on said output-time characteristics after the movementcompletion of said moving iron core.
 23. The state grasp device providedwith operation means for operating at least one kind of variation instate quantity, driving parameter, and remaining operating life of saidoperated apparatus or electromagnetic operating system on the basis ofat least one kind of information of time information, current valueinformation, and voltage value information at said inflection pointaccording to claim
 3. 24. The state grasp device according to claim 23,wherein there is provided signal transmission means for transmittingsignals when a change amount over time of said variation exceeds apredetermined value.
 25. The state grasp device provided with operationsmeans for operating at least one kind of variation in state quantity,driving parameter, and remaining operating life of said operatedapparatus or electromagnetic operating system on the basis of at leastone kind of information of current value information and voltage valueinformation at a feature time point according to claim
 6. 26. The stategrasp device according to claim 25, wherein there is provided signaltransmission means for transmitting signals when a change amount overtime of said variation exceeds a predetermined value.